DBMS Lab Manual CaseStudy

11.1 Tutorials using Oracle 9i & VB6.0………………..... 426 11.2 Tutorials using MS-Access & VB6.0.…………….... 448 11.3 Tutorials using MS-Sql & VB6.0…...……………..… 449 11.4 Compamy Database……………………..………….……. 453 11.5 Report Generation………………...…………………….… 495 11.6 Additional Examples……………………………….………. 499

Chapter 11

Application Development-Tutorials

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In Chapters 1 through Chapter 10, we have discussed database concepts and i am

sure that it would be incomplete if database application development is not

covered. This chapter is dedicated to fulfill this requirement. The aim is to describe

the steps involved in developing a database application for a small company using

Oracle9i as back-end and VB 6.0 as front-end. However, instead of starting with a

large application like the company database, we shall first present few simple

tutorials.

You would definitely get complete details of various issues related to the

design of a customized application development. The only requirement to

understand this chapter is know the basics of VB 6.0. This chapter starts with few

small tutorial examples and then it takes you to Software Requirement

Specification (SRS) of Company database and explains the procedures to create

forms, command buttons, VB code, and many more. By practicing this case study,

you can develop any other application package with out any additional efforts.

The entire chapter is divided into four parts each one considers a different

backend tool.

PART - I

11.1 TUTORIALS USING ORACLE9i & VB6.0

We shall begin with tutorials that use Oracle9i DBMS as back-end and VB6.0 as

front-end tool. It is assumed that the reader is aware of VB6.0 already so that

understanding the tutorials become easier.

Application Development: Tutorials 427

11.1.1 Tutorial - I

The aim of this tutorial is to:

Create a simple table 'Test' in Oracle9i with two attributes 'RegNo' and 'Name'

and develop an application in VB6.0 to add new records, browse, modify, and

delete the records.

We shall assume the following hardware and software:

Operating System: Windows XP Professional

Database: Oracle 9i

Front-End Tool: VB 6.0

Step-1: Go to the SQL window. Click on Start > All programs > Oracle-OraHome90 > Application Development > SQL Plus. Step-2: Type the following code in the SQL prompt:

CREATE TABLE Test ( RegNo VARCHAR2(10), Name VARCHAR2 (20) NOT NULL, PRIMARY KEY(RegNo)); Step-3: Click Start > Control Panel > Administrative tools > Data Sources(ODBC). Step-4: Press Add button and enter a name for the DSN (Data Source Name). Leave the rest

blank. In this example, it is named as “Elective”.

The screenshots of Step-3 and Step-4 are shown below:

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Step-5: Click Start > All Programs > Microsoft Visual Studio 6.0 > Microsoft Visual Basic 6.0. In the “New Project” Window, select “Standard EXE” icon and then click the “Open” button. You will see a new Project window and a form window with the default names “Project1” and “Form1”.

Step-6: Change Name property of the form to “Demo1” and the caption property to “Demo1”.

Step-7: Draw the following controls and assign the names as given below: Name Type Caption

Label1 label RegNo Label2 label2 Name txtRegNo Text box txtName Text box cmdFirst Command Button << Name Type Caption

cmdPrev Command Button < cmdNext Command Button > cmdLast Command Button >> cmdSave Command Button &Save cmdCancel Command Button &Cancel cmdDelete Command Button &Delete cmdExit Command Button Exit After creating these controls, the form should look like as shown in Figure 11.1.

Step-8: Before typing the program, do the following: Click Project > References and check Microsoft Active X Data Objects 2.5 Library. See Fig. 11.2.

Fig. 11.1 Layout of form Demo1

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Fig. 11.2 Setting of ActiveX Data Object Library

Step-9: Enter the code for the form load, and other controls as given in the next page.

Global Section

Option Explicit Dim DB As Connection Dim rstStudent As Recordset Cancel Button

Private Sub cmdCancel_Click() rstStudent.CancelUpdate rstStudent.Requery End Sub

Delete Button

Private Sub cmdDelete_Click() On Error Resume Next Dim intChoice If Not rstStudent.EOF Then intChoice = MsgBox("Are sure you want to delete?", vbYesNo + vbCritical) If intChoice = vbYes Then rstStudent.Delete rstStudent.MoveNext If rstStudent.EOF Then

rstStudent.MoveLast End If End If End If End Sub First Button (<<)

Private Sub cmdFirst_Click() On Error Resume Next rstStudent.MoveFirst cmdPrev.Enabled = False cmdNext.Enabled = True End Sub Last Button (>>)

Private Sub cmdLast_Click() On Error Resume Next rstStudent.MoveLast cmdNext.Enabled = False cmdPrev.Enabled = True End Sub

Next Button (>)

Private Sub cmdNext_Click() On Error Resume Next rstStudent.MoveNext If rstStudent.EOF Then rstStudent.MoveLast End If cmdPrev.Enabled = True End Sub

Previous Button (<)

Private Sub cmdPrev_Click() On Error Resume Next rstStudent.MovePrevious If rstStudent.BOF Then rstStudent.MoveFirst End If cmdNext.Enabled = True Exit Sub End Sub

New Button

Private Sub cmdNew_Click() rstStudent.AddNew 'Create a new record and clear txtRegNo.Text = "" txtName.Text = "" txtRegNo.SetFocus End Sub

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Save Button

Private Sub cmdSave_Click() On Error Resume Next rstStudent!RegNo = txtRegNo.Text rstStudent!Name = txtName.Text rstStudent.Update cmdFirst.Enabled = True cmdPrev.Enabled = True cmdNext.Enabled = True cmdLast.Enabled = True rstStudent.Requery End Sub

Form Load Section

Private Sub Form_Load() On Error Resume Next 'Create connection object (for Oracle database) Set DB = New Connection DB.Open "DSN=Elective;UID=Scott;PASSWORD=Tiger" 'Create recordset object Set rstStudent = New Recordset rstStudent.CursorLocation = adUseClient rstStudent.Open "Select * from Test", DB, adOpenDynamic, adLockOptimistic

'Bind the form controls to database fields Set txtRegNo.DataSource = rstStudent txtRegNo.DataField = "RegNo" Set txtName.DataSource = rstStudent txtName.DataField = "Name" 'Check for empty status of the table Dim count As Integer While Not rstStudent.EOF count = count + 1 rstStudent.MoveNext Wend If count = 0 Then 'no records cmdFirst.Enabled = False cmdPrev.Enabled = False cmdNext.Enabled = False cmdLast.Enabled = False MsgBox "No Records in the Table", vbExclamation, "Error" Else rstStudent.MoveFirst End If 'rstStudent.MoveFirst End Sub Exit Button

Private Sub cmdExit_Click() End End Sub


Step-10: Save the project with appropriate name (in this example it is “Demo1”). You can set the name of the project by selecting Project > Project1 properties and type “DatabaseDemo” in the Project Name text box and then click “OK” button (See Figure 11.3).

Step-11: Press F5 to run the application.

Fig. 11.3 Setting name to a Project Exercise

Create a new table called “Projects” with attributes ”PNo”, “PName”, and “RegNo”. Here RegNo is a foreign key, which references “RegNo” of “Student” table. Design a list box and a combo box. The combo box should be populated with student register numbers (or name). When a register number or name is selected from the combo box, the list box must be populated with all the projects the student is working on.

The next tutorial solvs this exercise and is named as Tutorial-II.

11.1.2 Tutorial - II

This tutorial is an extension of Tutorial-I and in fact the solution of the exercise

given in the previous section. However, we need to create a new table called

‚Projects‛ as shown below:

Step-1: CREATE TABLE Projects ( PNo INTEGER, PName VARCHAR2(20), RegNo VARCHAR2(10), PRIMARY KEY(PNo), FOREIGN KEY(RegNo) REFERENCES Test(RegNo));

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Step-2: Create a combo box and name it as “Combo1”. Step-3: Create a list box and name it as “List1”.

The other controls are same as the previous Tutorial. However, some new GUI

components have been added to this project. The first one is a menu and the

second one is a tool bar. We shall explain the steps involved in designing these

controls.

Step-4: To create a menu, click Tools > Menu Editor (ctrl + E). Add main menu items and sub menu items as shown in Figure 11.4.

Fig. 11.4 Menu Editor

Step-5: Creating a tool bar is little tricky. Click Add-ins > Add-in Manager… > Application

Wizard and then check the Loaded/Unloaded and Load on Startup boxes (see Figure (11.5). This step brings two items for the Add-ins called “Application Wizard” and “Toolbar Wizard”.


Fig. 11.5 Getting the Toolbar Wizard Step-6: Click on Add-Ins > Toolbar Wizard… and add the appropriate icons as shown in Figure

11.6.

Fig. 11.6 Toolbar Wizard after the icons are selected Step-7: After these steps, the form will look like as shown in Figure 11.7.

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Fig. 11.7 Final Form Step-8: Type the code for various controls as follows: (Recall that to add the code for each

button/menu item/toolbar icon, simply double click or single click on the appropriate control)

Option Explicit Dim DB As Connection Dim rstStudent As Recordset

Dim rstProject As Recordset Private Sub mnuCancel_Click() rstStudent.CancelUpdate rstStudent.Requery cmdSave.Enabled = False mnuSave.Enabled = False Toolbar1.Buttons.Item(2).Enabled = False End Sub

Private Sub mnuDelete_Click() On Error Resume Next Dim intChoice If Not rstStudent.EOF Then intChoice = MsgBox("Are sure you want to delete?", vbYesNo + vbCritical) If intChoice = vbYes Then rstStudent.Delete Combo1.RemoveItem (rstStudent!Name) rstStudent.MoveNext If rstStudent.EOF Then


rstStudent.MoveLast End If End If End If End Sub

Private Sub mnuNew_Click() rstStudent.AddNew 'Create a new record and clear txtRegNo.Text = "" txtName.Text = "" txtRegNo.SetFocus cmdSave.Enabled = True mnuSave.Enabled = True Toolbar1.Buttons.Item(2).Enabled = True End Sub

Private Sub mnuSave_Click() rstStudent!RegNo = txtRegNo.Text rstStudent!Name = txtName.Text rstStudent.Update cmdFirst.Enabled = True cmdPrev.Enabled = True cmdNext.Enabled = True cmdLast.Enabled = True Combo1.AddItem (rstStudent!Name) rstStudent.Requery cmdSave.Enabled = False mnuSave.Enabled = False Toolbar1.Buttons.Item(2).Enabled = False End Sub

Private Sub Toolbar1_ButtonClick(ByVal Button As MSComCtlLib.Button) On Error Resume Next Select Case Button.Key Case "New" rstStudent.AddNew 'Create a new record and clear txtRegNo.Text = "" txtName.Text = "" txtRegNo.SetFocus cmdSave.Enabled = True mnuSave.Enabled = True Toolbar1.Buttons.Item(2).Enabled = True Case "Save" On Error Resume Next rstStudent!RegNo = txtRegNo.Text rstStudent!Name = txtName.Text rstStudent.Update cmdFirst.Enabled = True cmdPrev.Enabled = True cmdNext.Enabled = True cmdLast.Enabled = True Combo1.AddItem (rstStudent!Name) rstStudent.Requery cmdSave.Enabled = False mnuSave.Enabled = False

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Toolbar1.Buttons.Item(2).Enabled = False Case "Undo" rstStudent.CancelUpdate rstStudent.Requery cmdSave.Enabled = False mnuSave.Enabled = False Toolbar1.Buttons.Item(2).Enabled = False Case "Delete" On Error Resume Next Dim intChoice If Not rstStudent.EOF Then intChoice = MsgBox("Are sure you want to delete?", vbYesNo + vbCritical) If intChoice = vbYes Then rstStudent.Delete rstStudent.MoveNext If rstStudent.EOF Then rstStudent.MoveLast End If End If End If Case "Help" 'ToDo: Add 'Help' button code. MsgBox "Under construction." End Select End Sub

Private Sub cmdCancel_Click() rstStudent.CancelUpdate rstStudent.Requery cmdSave.Enabled = False mnuSave.Enabled = False Toolbar1.Buttons.Item(2).Enabled = False End Sub Private Sub cmdDelete_Click() On Error Resume Next Dim intChoice If Not rstStudent.EOF Then intChoice = MsgBox("Are sure you want to delete?", vbYesNo + vbCritical) If intChoice = vbYes Then Combo1.RemoveItem (rstStudent!Name) rstStudent.Delete rstStudent.MoveNext If rstStudent.EOF Then rstStudent.MoveLast End If End If End If End Sub Private Sub cmdExit_Click() End End Sub

Private Sub cmdFirst_Click() On Error Resume Next


rstStudent.MoveFirst cmdPrev.Enabled = False cmdNext.Enabled = True End Sub Private Sub cmdLast_Click() On Error Resume Next rstStudent.MoveLast cmdNext.Enabled = False cmdPrev.Enabled = True End Sub Private Sub cmdNew_Click() rstStudent.AddNew 'Create a new record and clear txtRegNo.Text = "" txtName.Text = "" txtRegNo.SetFocus cmdSave.Enabled = True mnuSave.Enabled = True Toolbar1.Buttons.Item(2).Enabled = True End Sub

Private Sub cmdNext_Click() On Error Resume Next rstStudent.MoveNext If rstStudent.EOF Then rstStudent.MoveLast End If cmdPrev.Enabled = True End Sub

Private Sub cmdPrev_Click() On Error Resume Next rstStudent.MovePrevious If rstStudent.BOF Then rstStudent.MoveFirst End If cmdNext.Enabled = True Exit Sub End Sub Private Sub cmdSave_Click() On Error Resume Next rstStudent!RegNo = txtRegNo.Text rstStudent!Name = txtName.Text rstStudent.Update cmdFirst.Enabled = True cmdPrev.Enabled = True cmdNext.Enabled = True cmdLast.Enabled = True Combo1.AddItem (rstStudent!Name) rstStudent.Requery cmdSave.Enabled = False mnuSave.Enabled = False Toolbar1.Buttons.Item(2).Enabled = False

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End Sub Private Sub Combo1_Click() List1.Clear 'Populate combo box and list box Set rstProject = New Recordset rstProject.Open "Select PName from Projects,Test where Projects.RegNo =

Test.RegNo and Test.Name = " & "'" & Combo1.Text & "'", DB, adOpenDynamic, adLockOptimistic

While Not rstProject.EOF List1.AddItem (rstProject!PName) rstProject.MoveNext Wend End Sub Private Sub Form_Load() On Error Resume Next 'Create connection object (for Oracle database) Set DB = New Connection DB.Open "DSN=Elective;UID=Scott;PASSWORD=Tiger" 'Create recordset object Set rstStudent = New Recordset rstStudent.Open "Select * from Test", DB, adOpenDynamic, adLockOptimistic 'Bind the form controls to database fields Set txtRegNo.DataSource = rstStudent txtRegNo.DataField = "RegNo" Set txtName.DataSource = rstStudent txtName.DataField = "Name" 'Check for empty status of the table Dim count As Integer While Not rstStudent.EOF count = count + 1 rstStudent.MoveNext Wend If count = 0 Then 'no records cmdFirst.Enabled = False cmdPrev.Enabled = False cmdNext.Enabled = False cmdLast.Enabled = False MsgBox "No Records in the Table", vbExclamation, "Error" Else rstStudent.MoveFirst End If Combo1.ToolTipText = "Select the Student Name." List1.ToolTipText = "List of projects being operated by the above student" 'populate the combo box with names While Not rstStudent.EOF Combo1.AddItem (rstStudent!Name) rstStudent.MoveNext Wend rstStudent.MoveFirst cmdSave.Enabled = False mnuSave.Enabled = False


Toolbar1.Buttons.Item(2).Enabled = False End Sub Private Sub mnuExit_Click() End End Sub

Step-9: Finally, save the form and the project. In our example - “Demo2” is the form name and

“DataBaseDemo” is the name of the project. Step-10: Run the application and test it with some sample data. Exercise

Create a third table "Course" and add appropriate foreign keys. Modify the design presented in this section to incorporate this table too.

11.1.3 Tutorial - III

The primary purpose of this Tutorial-III is to develop an Enterprise Manager

Console (EMC) to maintain user accounts and the passwords. This console will

help the administrator to create, modify, and delete users. The passwords are

encrypted and stored in the database.

Another advantage of this application is that any database application can use

this package for security purposes. The steps needed to develop this application

are shown in the following steps. Since we have already shown detailed steps in

creating form(s), menus, and tool bar, this tutorial does not give the steps in detail.

Step-1: Create a table called “Users” in the SQL prompt as follows:

CREATE TABLE Users ( id VARCHAR2(10), passwd VARCHAR2(10) NOT NULL, PRIMARY KEY(id));

Step-2: Create a new form and give the “frmEMC” and its caption property as “Enterprise

Manager Console”. Save the project by giving the name as “Security”. Step-3: The form should have the following controls:

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Control Type Property Name Caption Frame Frame1 New User Label User Name - Label Password - Label Confirm Password - Text box txtUsrName - Text box txtPass - Text box txtConform - Command button cmdCancel &Cancel Command button cmdSave &Save Frame Frame2 Existing Users DataGrid DataGrid1 Password Table Command button cmdShow S&how users Command button cmdConnect Connec&t Frame Frame3 Privileges Check box CheckM - Check box CheckD - Label Label3 Allow Modify Label Label4 Allow Delete ADODC Adodc1 Adodc1

Connection String: Provider=MSDAORA.1;User ID=scott;Persist Security Info=False Password: Tiger Record Source: SELECT ID, passwd FROM USERS ORDER BY ID UserName: Scott Step-4: Let us see what the main menus are and sub menu items that are required for this

application. File Edit Help New user… Ctrl+N Change Password… Contents Save user Ctrl+S Modify User… About Exit Ctrl+X Delete User… Ctrl+D

Step-5: The next task which needs to be done is the creation of tool bar as shown in Figure

11.8 (this figure shows the complete form also). Step-6: Type the following code for various controls of this form.

Option Explicit Dim DB As Connection Dim rstUser As Recordset Private Sub cmdCancel_Click() rstUser.CancelUpdate Disable_fields End Sub


Private Sub cmdConnect_Click() MsgBox "Plug-in your application (main form) here ......", vbInformation End Sub Private Sub cmdSave_Click() On Error GoTo err1 Dim strEString As String Set rstUser = New Recordset rstUser.Open "Select * from users order by id", DB, adOpenDynamic,

adLockOptimistic rstUser.AddNew rstUser!id = txtUsrName.Text strEString = Encrypt_password rstUser!passwd = strEString If txtPass = txtconfirm Then rstUser.Update Disable_fields Else MsgBox "Passwords do not match, please reenter", vbCritical, "Password Error" txtPass.SetFocus SendKeys "{Home}+{End}" End If Exit Sub err1: MsgBox Err.Description End Sub Private Sub cmdShow_Click() Set DataGrid1.DataSource = Adodc1 Adodc1.Refresh End Sub Private Sub Form_Load() On Error Resume Next Set DB = New Connection DB.Open "DSN=Elective;UID=scott;password=tiger;" Set rstUser = New Recordset rstUser.Open "Select * from Users order by id", DB, adOpenDynamic,

adLockOptimistic ' a dummy record is created rstUser.AddNew rstUser!id = "dummy" rstUser!passwd = "dummy" rstUser.Update Set txtUsrName.DataSource = rstUser txtUsrName.DataField = "id" Set txtPass.DataSource = rstUser txtPass.DataField = "passwd" DataGrid1.AllowAddNew = False DataGrid1.AllowDelete = False DataGrid1.AllowUpdate = False Disable_fields cmdShow.SetFocus End Sub

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Private Sub mnuchange_Click() MsgBox "Left as Exercise", vbInformation End Sub Private Sub mnuDelete_Click() Dim intChoice As Integer Dim strIN As String strIN = InputBox("Enter the User Name") If strIN = "" Then 'user has pressed Cancel button Exit Sub End If Set rstUser = New Recordset rstUser.Open "Select * from Users where id = " & "'" & strIN & "'", DB,

adOpenDynamic, adLockOptimistic If rstUser.EOF Then MsgBox "Record not found, can't delete", vbExclamation, "Missing Record" Else intChoice = MsgBox("Are you sure you want to Delete?", vbCritical + vbYesNo,

"Delete") If intChoice = vbYes Then rstUser.Delete End If End If End Sub Private Sub mnuNew_Click() Enable_fields txtUsrName.SetFocus End Sub Private Sub mnuSave_Click() cmdSave_Click End Sub Private Sub Toolbar1_ButtonClick(ByVal Button As MSComCtlLib.Button) On Error Resume Next

Select Case Button.Key Case "Help" 'ToDo: Add 'Help' button code. 'MsgBox "Add 'Help' button code." Case "Delete" mnuDelete_Click Case "Undo" cmdCancel_Click Case "Save" cmdSave_Click Case "New" Enable_fields txtUsrName.SetFocus Case "Open" 'ToDo: Add 'Open' button code. End Select End Sub

Private Sub mnuExit_Click() End End Sub Private Sub Disable_fields() txtUsrName.Text = "" txtPass.Text = "" txtconfirm.Text = "" txtUsrName.Enabled = False txtPass.Enabled = False txtconfirm.Enabled = False Frame2.Enabled = False End Sub Private Sub Enable_fields() Frame2.Enabled = True txtUsrName.Enabled = True txtPass.Enabled = True txtconfirm.Enabled = True txtUsrName.Text = "" txtPass.Text = "" CheckM.Value = 0 CheckD.Value = 0 End Sub Private Function Encrypt_password() As String Dim strpw As String Dim s As String Dim c As Integer Dim intIndex As Integer Dim strArray(10) As String Dim strFinal As String strpw = txtPass.Text 'gets the leftmost character strpw = txtPass.Text For intIndex = 1 To Len(strpw) s = Mid(strpw, intIndex, 1) 'encrypt the password c = Asc(s) + 5 strArray(intIndex) = Chr(c) 'append the character to the final string strFinal = strFinal + strArray(intIndex) Next intIndex Encrypt_password = strFinal End Function

Private Sub txtPass_Validate(Cancel As Boolean) If Len(txtPass.Text) < 6 Or Len(txtPass.Text) > 10 Then MsgBox "Password should be minimum 6 characters and not more than 10

characters", vbExclamation, "Error" txtPass.SetFocus SendKeys "{Home}+{End}" Cancel = True End If End Sub

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Fig. 11.8 Security form

Private Sub txtUsrName_Validate(Cancel As Boolean) If Len(txtUsrName.Text) < 3 Or Len(txtUsrName.Text) > 10 Then MsgBox "Username should be minimum 3 characters and not more than 10

characters", vbExclamation, "Error" txtUsrName.SetFocus SendKeys "{Home}+{End}" Cancel = True End If End Sub

Step-7: Create a second form with name “frmLogin” and caption “Login”. Save the form as

“frmLogin” (See Figure 11.9).


Fig. 11.9 Login Form Step-8: Type the code for this as shown below:

Dim DB As Connection Dim rstId As Recordset Public LoginSucceeded As Integer Private Sub cmdCancel_Click() 'set the global var to false 'to denote a failed login LoginSucceeded = False Unload Me End Sub

Private Sub cmdOK_Click() If txtUserName = "manager" And txtPassword = "bit" Then LoginSucceeded = 1 'Administrator txtUserName.Text = "" txtPassword.Text = "" Me.Hide frmEMC.Show vbModal ElseIf RecStatus = True Then LoginSucceeded = 2 'Ordinary users MsgBox "Other Users" txtUserName.Text = "" txtPassword.Text = "" Me.Hide Else MsgBox "Invalid Password, try again!", , "Login" txtUserName.SetFocus SendKeys "{Home}+{End}" End If End Sub Private Function RecStatus() As Boolean Dim strUsername As String Dim strPasswd As String Dim strSQL As String strUsername = txtUserName.Text strPasswd = txtPassword.Text strPasswd = Encrypt_password

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Set rstId = New Recordset rstId.Open "Select id from Users where id = " & "'" & strUsername & "'" & "And

passwd =" & "'" & strPasswd & "'", DB, adOpenStatic, adLockOptimistic If rstId.EOF Then RecStatus = False 'Invalid user Else RecStatus = True 'User found End If End Function Private Sub Form_Load() Set DB = New Connection DB.Open "DSN=Elective;UID=scott;password=tiger;" End Sub Private Function Encrypt_password() As String Dim strpw As String Dim s As String Dim c As Integer Dim intIndex As Integer Dim strArray(10) As String Dim strFinal As String strpw = txtPassword.Text 'gets the leftmost character strpw = txtPassword.Text For intIndex = 1 To Len(strpw) s = Mid(strpw, intIndex, 1) 'encrypt the password c = Asc(s) + 5 strArray(intIndex) = Chr(c) 'append the character to the final string strFinal = strFinal + strArray(intIndex) Next intIndex Encrypt_password = strFinal End Function

PART - II

11.2 TUTORIAL USING MS-Access & VB6.0

All the examples shown in Part-I used Oracle9i as back-end. Let us show an

example with MS-Access as back-end in this section. However, we shall retain the

front-end as VB6.0 only.

The design using MS-Access is not much different from Tutorial-I of Part-I. All

that we need to do is to change the code in the FormLoad section as given below: Private Sub Form_Load()


'On Error Resume Next Set DB = New Connection 'For MS-Access Databse use the following connection 'DB.Open "Provider=Microsoft.Jet.OLEDB.4.0;Data Source=D:\DBMS\Tutorial-

I\Demo.mdb;Mode=ReadWrite|Share Deny None;Persist Security Info=False"

'Create recordset object Set rstStudent = New Recordset rstStudent.Open "Select * from Test", DB, adOpenDynamic, adLockOptimistic 'Bind the form controls to database fields Set txtRegNo.DataSource = rstStudent txtRegNo.DataField = "RegNo" Set txtName.DataSource = rstStudent txtName.DataField = "Name" …………… End Sub

The database file Demo.mdb with the table name 'Test' should be created in MS-

Acces with the same set of attributes as shown earlier. The above code (bold letters)

is a partial one and it is assumed to be in the folder: D:\DBMS\Tutorial-I. The rest

of the code is same as Tutorial-I. You don't need to change anything else at all.

PART - III

11.3 TUTORIAL USING SQL Server & VB6.0

The Tutorials given in the earlier sections did not cover a very important control

called "FlexGrid". The purpose of this section is to include the FlexGrid control and

demonstrate its usage in a typical application.

Let us adopt the same procedure as we did for the other tutorials too.

However, one major change that we introduce in this example is use of SQL Server

2000 as the backend database instead of Oracle 9i.

The objective of this application is to create a simple table called "Product" in

SQL Server and add data records using a flex grid control. Let us make things

clear! Hither to, we have used many text boxes and/or combo boxes to enter the

data. In addition, at any point of time we could add only one record. Now, using

this small application we will be able to add as many records as needed and save

all of them at one go. We shall implement this using the flex grid control of VB 6.0.

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Fig. 11.10 "Product" Table structure Step-1: Create a DSN called "T1" for SQL Server. The procedure is same as that of the

example shown in Section 11.4.4. However, you must select an appropriate "Data Source" i.e. SQL Server) from the window "Create New Data Source".

Step-2: Create a table called "Product" in SQL Server (see figure 11.10). Step-3: The next task is to create a form in VB with various controls as shown in Figure 11.11.

Fig. 11. 11 Data entry form for Product table with a FlexGrid Control Notice that the form has three text boxes and a combo box. In addition, we have a flexgrid called

"Grid1" where multiple data records be added. You can notice also that every time a

new record is added, by pressing "Add" button, the partial sum is shown in a label box against "Total".

Step-4: After creating the layout with various controls, type the code for each button and Form

Load section as given below:

Option Explicit Dim cn As ADODB.Connection Dim rstemp As New ADODB.Recordset Dim rsgrn As New ADODB.Recordset Dim Sum As Double 'to compute partial sum Private Sub Form_Load() Call initgrid Set cn = New ADODB.Connection 'The back end used is SQL Server

'change the user name and password for your settings cn.Open "DSN=T1;UID=sa;PASSWORD=bit" 'populate the combo box cmbCode.AddItem (100) cmbCode.AddItem (200) cmbCode.AddItem (300) cmbCode.AddItem (400) cmbCode.AddItem (500) cmbCode.AddItem (600)

lblDate.Caption = Date

Grid1.Col = 0 Grid1.row = 0

'form sizing Me.Height = 6850 Me.Width = 9270

cmbCode.Visible = True End Sub Public Sub initgrid() Dim s As String s$ = "<SR_NO|Product ID|Description|Unit|Quantity|Price|Net Price" Grid1.FormatString = s$ Grid1.ColWidth(1) = 1200 Grid1.ColWidth(2) = 2000 Grid1.ColWidth(3) = 800 Grid1.ColWidth(4) = 1000 Grid1.ColWidth(5) = 1000 Grid1.ColWidth(6) = 1370

Grid1.ColAlignment(4) = 7 Grid1.ColAlignment(5) = 7 Grid1.ColAlignment(6) = 7 Grid1.Rows = 2 End Sub

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Private Sub cmdAdd_Click() If txtprice.Text <> "" And txtqty.Text <> "" And cmbCode.Text <> "" Then If IsNumeric(txtprice.Text) And IsNumeric(txtqty.Text) Then ' add to the grid Dim row As Integer row = Grid1.Rows - 1 Grid1.TextMatrix(row, 0) = row Grid1.TextMatrix(row, 1) = cmbCode.Text Grid1.TextMatrix(row, 2) = txtName.Text Grid1.TextMatrix(row, 3) = "Ltr" Grid1.TextMatrix(row, 4) = txtqty.Text Grid1.TextMatrix(row, 5) = txtprice.Text Grid1.TextMatrix(row, 6) = Format((Val(txtqty.Text) * Val(txtprice.Text)), ".00")

'Display the partial total Sum = Sum + (Val(txtqty.Text) * Val(txtprice.Text)) lblTotal.Caption = Sum Grid1.Rows = Grid1.Rows + 1 cmbCode.Text = "" txtName.Text = "" txtqty.Text = "" txtprice.Text = "" cmbCode.SetFocus Else MsgBox "Invalid data", vbCritical End If Else MsgBox "No data in the fields", vbCritical End If Exit Sub databaseerror: cn.RollbackTrans rsgrn.Close MsgBox "The following error has occured while saving data : " & Chr(13) +

Chr(10) & " No : " & Err.Number & " Description : " & Err.Description End Sub Private Sub cmdSave_Click() Dim i As Integer

'whole grid is empty If Grid1.Rows < 3 Or Grid1.TextMatrix(1, 1) = "" Then MsgBox "There is no record to save" Exit Sub End If

On Error GoTo databaseerror

'start saving Set rsgrn = New ADODB.Recordset rsgrn.Open "select * from Product", cn, adOpenDynamic, adLockOptimistic

'start transaction cn.BeginTrans


For i = 1 To Grid1.Rows - 2 rsgrn.AddNew rsgrn.Fields("grnno") = Val(Grid1.TextMatrix(i, 1)) rsgrn.Fields("pcode") = Grid1.TextMatrix(i, 2) rsgrn.Fields("value") = Val(Grid1.TextMatrix(i, 3)) rsgrn.Fields("quantity") = Val(Grid1.TextMatrix(i, 4)) rsgrn.Update Next i

'commit transaction to save changes cn.CommitTrans

MsgBox "The data has been saved successfully", vbInformation, "FMC United"

rsgrn.Close

Grid1.Clear Call initgrid 'txtgrn.Text = Val(txtgrn.Text) + 1 cmbCode.SetFocus Sum = 0 lblTotal.Caption = Sum Exit Sub

databaseerror: cn.RollbackTrans rsgrn.Close MsgBox "The following error has occured while saving data : " & Chr(13) +

Chr(10) & " No : " & Err.Number & " Description : " & Err.Description End Sub Private Sub cmdCancel_Click() Unload Me End Sub Private Sub cmdClear_Click() Grid1.Clear Grid1.Rows = 2 cmbCode.SetFocus End Sub

PART - IV

11.4 COMPANY DATABASE

Though there are many problems for automation, we have selected a very simple

problem called the Company Database. This problem has been discussed already

in Chapter 1; but now we shall describe its implementation issues. Following is a

simple abstract of the problem domain for the Company database.

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1. Let us assume that our Company wants to automate its entire

administration work.

2. The Company has many employees working in various departments. Each

employee has SSN, Name, Address, Sex, Salary, etc.

3. It has several departments. Each department has a manager who is also an

employee of the company. A department may be located at more than one

place.

4. Every department controls one or more projects.

5. Projects are identified by Project Number, Project Name, and so on.

6. An employee is allowed to work for a particular department. However, he

or she can work on more than one project.

7. Salary is paid to employees depending upon how many hours they work

on project(s).

8. Employees may have more than one dependents and it is required that

their information also must be stored in the database.

Since maintaining all these information manually becomes cumbersome, the

company wishes to automate the entire process. For this case study, we prefer to

use Oracle9i and VB 6.0 because of their popularity in the industry and their rich

GUI capabilities.

11.4.1 Conceptual Design

This section talks about the conceptual design aspects for the problem described in

Section 11.4. Recall that Section 3.2 explained the conceptual design of this problem

and Figure 3.13 depicted the ER diagram for the same.

In addition, Figure 4.2 showed the table structure for the entire application

after normalization. Remember, to solve any new problem, you are expected to

start with an ER diagram, translate into tables, and normalize these tables at least

up to BCNF level. In our example, all these steps have already been done and so

we can proceed to create these tables in Oracle9i. The next section does this.

11.4.2 Creating Tables in Oracle9i

The first step in the implementation process is to create all tables using Oracle SQL.

This section explains the steps required to achieve this goal.

Step-1: In the SQL prompt, type the following programs: (alternatively, you can enter these

programs in a notepad and copy and paste in the SQL prompt).


CREATE TABLE Employee ( SSN char(9) not null, Name varchar2(20) not null, BDate date, Address varchar2(30), Sex char, Salary number(10,2), SuperSSN char(9), Primary Key(SSN) );

CREATE TABLE Department ( DNumber number(2) not null, DName varchar2(10) not null, MgrSSN char(9), MgrStartDate date, Primary Key(DNumber), foreign key(MgrSSN) references Employee(SSN) on delete cascade ); ALTER TABLE Employee ADD DNo number(4) not null references Department(DNumber) on delete cascade; CREATE TABLE Project ( PNumber number(2) not null, PName varchar(10) not null, Plocation varchar2(15), DNum number(2) not null, Primary Key(PNumber), Unique(PName), foreign key(DNum) references Department(DNumber) on delete cascade );

CREATE TABLE Dependent ( ESSN char(9) not null, Dependent_Name varchar2(15) not null, Sex char, BDate date, Relationship varchar2(10), Primary Key(ESSN, Dependent_Name), foreign key(ESSN) references Employee(SSN) on delete cascade );

CREATE TABLE Dept_Locations ( DNumber number(2) not null, Dlocation varchar2(15),

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Primary Key(DNumber, Dlocation), foreign key(DNumber) references Department(DNumber) on delete cascade ); CREATE TABLE Works_On ( ESSN char(9) not null, PNo number(2) not null, Hours number(3,1) not null, Primary Key(ESSN, PNo), foreign key(ESSN) references Employee(SSN) on delete cascade, foreign key(PNo) references Project(PNumber) on delete cascade );

CREATE VIEW SSNHrs as SELECT ESSN, Sum(Hours) as TotalHrs FROM Works_On GROUP BY ESSN; COMMIT;

11.4.3 Front-End Design Requirements

We must now decide the design of several forms for populating the tables. This

section describes the steps to design various menus, forms, and navigation details.

Following requirements must be met:

1. To provide access privileges in using the application, we shall provide two

users: (1) a super user called as "ceo" with password "apple" (2) an ordinary

clerk "clerk" with password "lion". The user "ceo" holds all the privileges

(add, delete, and modify), whereas the user clerk can not delete any

records.

2. There should be a form to show the employee records with search options.

The user must be able to search based upon SSN/Name of the employee.

Also the records must be shown in a tabular form.

3. A set of forms for adding employee records, department records, project

records, work details, department locations, etc. must be designed. These

forms may be supported with browsing facility. Also facility to modify and

delete the records shall be provided.

4. A separate form for calculating the total wages for employees is to be made

as part of the project.

5. Finally, some meaningful and also useful reports using the VB's data

reports must be designed.


11.4.4 Setting up Data Source Name (DSN)

The first thing you must do is to set up the ODBC connectivity to the Oracle

database (recall, you have done the same work in Tutorial-I). In order to do this

you must execute the following steps:

Step-1: Start > Control Panel. Double click on Administrative Tools and double click on Data

Sources (ODBC). You will see the screen similar to the one shown in Figure 11.12.

Fig. 11.12 DSN settings

Step-2: Press Add button to create a new DSN source. After pressing Add button, you should

see a screen as shown in Figure 11.13. Step-3: Select Microsoft ODBC for Oracle and then click on Finish button. Then another

small window appears as shown in Figure 11.14.

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Fig. 11.13 Selecting a new Data Source

Fig. 11.14 Creating new (Data Source Name) DSN

Step-4: Enter "empl" in Data Source Name and then press OK. There is no need to enter

other details in this window.

With this step, you have successfully created a new data source name called

"empl" for Oracle ODBC.

11.4.5 Design of Login Form (frmLogin)

The main objective of a login form is to get the user name and password. If it

matches with the predefined values, the user will be allowed to use the database


application with some assigned privileges. In case if it does not match the login

screen, the login window should appear again. With this requirement in mind, we

shall show how to create the login form. The necessary steps are shown below:

Step-1: Create a new Login form with name as "frmLogin" and caption property set to "login".

The controls are as shown in Figure 11.15.

Fig. 11.15 Login Form Step-2: Double click on "OK" button and "Cancel" button and type the appropriate code as

shown below:

Option Explicit Public LoginSucceeded As Integer Private Sub cmdCancel_Click() 'set the global var to false 'to denote a failed login LoginSucceeded = 0 Unload Me End Sub Private Sub cmdOK_Click() 'check for correct password If txtUserName = "ceo" And txtPassword = "apple" Then 'login successfull for super user LoginSucceeded = 1 Me.Hide frmMainForm.Show ElseIf txtUserName = "clerk" And txtPassword = "lion" Then 'login successfull for clerk LoginSucceeded = 2 Me.Hide frmMainForm.Show Else 'login failed LoginSucceeded = 0 MsgBox "Invalid User Name/Password, try again!", , "Login" txtUserName.SetFocus SendKeys "{Home}+{End}" End If

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'clear the field txtPassword.Text = "" End Sub

11.4.6 Design of Main Form

In this section you will study about the methodology in creating the opening or

main form which contains the navigation details in the form of submenus. Figure

11.16 shows the complete menu.

Fig. 11.16 The Main Menu Layout

Step-1: Create the above menu by invoking the menu editor and type the following details: Caption Name Shortcut &File DbAcc &Login Dblogin Ctrl+N E&xit DbExit Ctrl+Q &Divisions mnucmp &Employee Details mnuemp E&mployees mnuepl Ctrl+M &Work Info mnuwrks Ctrl+W D&epartment Details mnuDep Departments… mnuDept Ctrl+E Department &Locations mnudeploc Ctrl+L &Projects mnuProj &Reports mnurep Employee Details mnuREmp Employee Wage Details mnuRDept Project Details mnuRProject &Help AppHelp &Technical Support Appulse F2 About ApplAbout

File Divisions Reports Help

Login Ctrl+N Exit Ctrl+Q

Employee Details Department Details Projects

Employees Work Info

Employee Details Employee Wage Details Department Details Project Details

Technical Support F2 About


Figure 11.17 shows the "frmMainForm" and its Picture property is set with the

bitmap image.

Fig. 11.17 The Main Form Step-2: Type the following code by double clicking the appropriate menu item.

Dim db As Connection Private Sub ApplAbout_Click() frmAbout.Show vbModal End Sub

Private Sub Appluse_Click() frmTechnical.Show End Sub Private Sub DbExit_Click() End End Sub Private Sub DbLogin_Click() frmLogin.Show vbModal End Sub Private Sub imgEmp_Click()

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frmEmployee.Show vbModal End Sub Private Sub mnuDept_Click() frmDept.Show vbModal End Sub Private Sub mnudeploc_Click() frmDepLoc.Show vbModal End Sub Private Sub mnuepl_Click() frmEmployee.Show vbModal End Sub Private Sub mnuproj_Click() frmProject.Show vbModal End Sub Private Sub mnuRDept_Click() rptDepartment.Show vbModal End Sub Private Sub mnuREmp_Click() rptEmployee.Show vbModal End Sub Private Sub mnuREmpWages_Click() Dim choice As Integer If DataEnvironment1.rscmdWages.State = adStateOpen Then DataEnvironment1.rscmdWages.Close End If choice = InputBox("Please enter the Wages/Hour") DataEnvironment1.cmdWages Val(choice) Load rptWages rptWages.Show vbModal End Sub Private Sub mnuRProject_Click() rptProject.Show vbModal End Sub Private Sub mnuwrks_Click() frmWorks.Show vbModal End Sub

Step-3: Save the "frmMainForm" and do not execute!

11.4.7 Design of Employee Form

The design of Employee form is same as other forms that have been created

already. In fact, this form enables the users to maintain all the employee data. You


can add, delete, modify, search, add dependent details, and many more. These

tasks can be achieved either by clicking the drop down menus or the tool bar icons.

Below are the steps needed to create the Employee form.

Step-1: Click Project > Add Form. Draw various controls as indicated in Figure 11.18

Fig. 11.18 Employee form Step-2: The controls that you see in the Figure are DataGrid1, a command button (Show

Dependents), a command button (Close), a tool bar, and menu items. The names of the menu items can be taken from the code that is given next.

Step-3: Save the form as "frmEmployee". Step-4: Type the code as listed below:

Option Explicit Dim db As Connection Dim rstEmployee As Recordset Dim rstEmpFind As Recordset Public strSSN As String 'to acces in frmModifyEmp form Private Sub cmdClose_Click() Unload Me End Sub Private Sub cmdShow_Click() Dim choice As String If DataEnvironment1.rscmdDependents.State = adStateOpen Then DataEnvironment1.rscmdDependents.Close End If choice = DataGrid1.Columns(1) DataEnvironment1.cmdDependents choice

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Load rptDependent rptDependent.Show vbModal End Sub Private Sub mnuDelete_Click() Dim ChoiceSSN As String Dim Response As Integer Dim strSQL As String Response = MsgBox("Are you sure you want to Delete?", vbYesNo, "Confirm

Deletion") If Response = vbYes Then DataGrid1.AllowDelete = True ChoiceSSN = DataGrid1.Columns(1) strSQL = "Delete from Employee where SSN = " & ChoiceSSN db.Execute strSQL Call Reset DataGrid1.AllowDelete = False End If End Sub Private Sub mnuExit_Click() Unload Me End Sub Private Sub mnuModify_Click() strSSN = DataGrid1.Columns(1) frmModifyEmp.Show vbModal Call Reset End Sub Private Sub mnuName_Click() Dim ChoiceName As String ChoiceName = InputBox("Type the Employee's Name", "Search by Name...") ChoiceName = StrConv(ChoiceName, vbUpperCase) If ChoiceName <> "" Then 'user has pressed OK button 'cancel button returns empty string Set rstEmpFind = New Recordset rstEmpFind.CursorLocation = adUseClient rstEmpFind.Open "Select * from Employee where Name = " & "'" & ChoiceName

& "'", db, adOpenStatic, adLockReadOnly If rstEmpFind.EOF Then MsgBox "Employee does not exist", vbCritical, "Employee Not Found" Else Set DataGrid1.DataSource = rstEmpFind DataGrid1.Refresh End If End If End Sub Private Sub mnuNew_Click() frmAddEmployee.Show vbModal End Sub Private Sub mnuOpenDep_Click() frmDepen.Show vbModal End Sub

Private Sub mnuRefresh_Click() Set DataGrid1.DataSource = rstEmployee DataGrid1.Refresh End Sub Private Sub mnuSSN_Click() Dim ChoiceSSN As String ChoiceSSN = InputBox("Enter the SSN") If ChoiceSSN <> "" Then 'user has pressed OK button 'cancel button returns empty string Set rstEmpFind = New Recordset rstEmpFind.CursorLocation = adUseClient rstEmpFind.Open "Select * from Employee where SSN = " & "'" & ChoiceSSN &

"'", db, adOpenStatic, adLockReadOnly If rstEmpFind.EOF Then MsgBox "Employee does not exist", vbCritical, "Employee Not Found" Else Set DataGrid1.DataSource = rstEmpFind DataGrid1.Refresh End If End If End Sub Private Sub Toolbar1_ButtonClick(ByVal Button As MSComCtlLib.Button) On Error Resume Next Select Case Button.Key Case "voc" 'ToDo: Add 'voc' button code. 'MsgBox "Add 'voc' button code." Case "Redo" 'rstEmployee.MoveFirst Set DataGrid1.DataSource = rstEmployee DataGrid1.Refresh Exit Sub Errorhandler: MsgBox "Error....", vbExclamation, "Error" Case "Undo" 'ToDo: Add 'Undo' button code. 'MsgBox "Add 'Undo' button code." Case "New" frmAddEmployee.Show vbModal Call Reset Case "Open" mnuOpenDep_Click Case "Save" 'ToDo: Add 'Save' button code. 'MsgBox "Add 'Save' button code." Case "Delete" mnuDelete_Click Case "Find" mnuSSN_Click Case "Help" 'ToDo: Add 'Help' button code. 'MsgBox "Add 'Help' button code." End Select

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End Sub Private Sub Form_Load() 'The user is a clerk - no access to delete button If frmLogin.LoginSucceeded = 2 Then mnuDelete.Enabled = False 'Remove the Delete (index is 6) button Toolbar1.Buttons.Item(6).Enabled = False End If Set db = New Connection db.Open "DSN=EMPL;UID=SCOTT;PASSWORD=TIGER;" Set rstEmployee = New Recordset rstEmployee.CursorLocation = adUseClient rstEmployee.Open "Select * from Employee order by TO_NUMBER(SSN)", db,

adOpenStatic, adLockReadOnly Set DataGrid1.DataSource = rstEmployee DataGrid1.Refresh End Sub Private Sub Reset() Set rstEmployee = New Recordset rstEmployee.CursorLocation = adUseClient rstEmployee.Open "Select * from Employee order by TO_NUMBER(SSN)", db,

adOpenStatic, adLockReadOnly Set DataGrid1.DataSource = rstEmployee DataGrid1.Refresh End Sub

11.4.8 Design of AddEmployee Form & Dependents Form

To make the Employee form work successfully, we need two more form, i.e. to add

new employees to the database and add dependents details for the employees. Let

us create two forms to accomplish this task.

Step-1: Create a new form and name it as "frmAddEmployee" and save it with the name. Step-2: Add the following controls as given below: Control Type Name Property Caption Property Text Box txtSSN - Text Box txtName - Combo Box cboDay - Combo Box cboMonth - Combo Box cboYear - Text Box txtAddr - Combo Box cboSex - Text Box txtSalary - Combo Box cboSSSN Combo Box cboDNo - Command Button cmdAdd Add Command button cmdCancel Cancel


The Figure 11.19 shows the form with these controls and the labels.

Fig. 11.19 frmAddEmployee Form Step-3: Type the code as shown below:

Option Explicit Dim db As Connection Dim rstEmployee As Recordset Dim rstDept As Recordset Dim rstSuperSSN As Recordset Private Sub cmdAdd_Click() On Error GoTo err1 Dim strDate As String Dim UsrDate As Date Dim CurrentDate As Date strDate = cboDay.Text + "/" + cboMonth.Text + "/" + cboYear.Text UsrDate = Format(strDate, "dd/mmm/yyyy") 'convert string to date CurrentDate = Format(Now, "dd/mmm/yyyy") 'convert string to date If Not UsrDate > CurrentDate Then rstEmployee!SSN = txtSSN.Text rstEmployee!Name = txtName.Text rstEmployee!BDate = strDate rstEmployee!Address = txtAddr.Text rstEmployee!Sex = cboSex.Text rstEmployee!Salary = Val(txtSalary.Text) rstEmployee!SuperSSN = cboSSSN.Text rstEmployee!DNo = Val(cboDNo.Text) rstEmployee.Update Unload Me Else

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MsgBox "Date of birth exceeds the current date", vbCritical, "Error in Birth date" cboDay.SetFocus strDate = cboDay.Text + "/" + cboMonth.Text + "/" + cboYear.Text End If Exit Sub err1: MsgBox Err.Description + Chr(13) + Chr(10) + "One or more fields may be empty",

vbCritical, "Error" End Sub Private Sub cmdCancel_Click() 'Cancels the changes done to new record rstEmployee.CancelUpdate Unload Me End Sub Private Sub Form_Load() Set db = New Connection db.Open "DSN=EMPL;UID=SCOTT;PASSWORD=TIGER;" Set rstEmployee = New Recordset rstEmployee.CursorLocation = adUseClient rstEmployee.Open "Select * from Employee", db, adOpenDynamic,

adLockOptimistic rstEmployee.AddNew txtSSN.Text = "" txtName.Text = "" txtAddr.Text = "" txtSalary.Text = "" cboSSSN.Text = "" cboDNo.Text = "" 'populate Department Number Set rstDept = New Recordset rstDept.Open "Select DNumber from Department", db, adOpenStatic,

adLockReadOnly While Not rstDept.EOF cboDNo.AddItem rstDept!DNumber rstDept.MoveNext Wend 'populate supervisor SSN Set rstSuperSSN = New Recordset rstSuperSSN.Open "Select SSN from Employee ", db, adOpenStatic,

adLockReadOnly While Not rstSuperSSN.EOF cboSSSN.AddItem rstSuperSSN!SSN rstSuperSSN.MoveNext Wend 'set default value cboSex.Text = "M" 'Populate Day Dim intDay As Integer intDay = 1 While intDay <= 31 cboDay.AddItem intDay intDay = intDay + 1 Wend


'Populate Month cboMonth.AddItem "Jan" cboMonth.AddItem "Feb" cboMonth.AddItem "Mar" cboMonth.AddItem "Apr" cboMonth.AddItem "May" cboMonth.AddItem "Jun" cboMonth.AddItem "Jul" cboMonth.AddItem "Aug" cboMonth.AddItem "Sep" cboMonth.AddItem "Oct" cboMonth.AddItem "Nov" cboMonth.AddItem "Dec" 'Populate Year Dim intYear As Integer Dim strYear As String Dim intY As Integer intYear = 1947 strYear = Right(Format(Date, "dd/mm/yyyy"), 4) intY = Val(strYear) While intY >= intYear cboYear.AddItem intY intY = intY - 1 Wend End Sub Private Sub txtAddr_Validate(Cancel As Boolean) txtAddr.Text = StrConv(txtAddr.Text, vbUpperCase) If txtAddr.Text = "" Then MsgBox "Incomplete or blank field not allowed!", vbCritical + vbOKOnly,

"ERROR" Cancel = True End If End Sub Private Sub txtSalary_Validate(Cancel As Boolean) If Not IsNumeric(txtSalary.Text) Or txtSalary.Text = "" Then MsgBox "Only numbers are allowed!", vbCritical + vbOKOnly, "ERROR" Cancel = True End If End Sub Private Sub txtSSN_Validate(Cancel As Boolean) 'txtSSN.Text = StrConv(txtSSN.Text, vbUpperCase) If txtSSN.Text = "" Then MsgBox "Blank field not allowed. Enter valid SSN", vbCritical + vbOKOnly,

"ERROR" Cancel = True ElseIf Len(txtSSN.Text) > 9 Then MsgBox "Enter SSN not more than 9 Characters", vbCritical + vbOKOnly,

"ERROR" Cancel = True End If End Sub

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Private Sub txtName_Validate(Cancel As Boolean) txtName.Text = StrConv(txtName.Text, vbUpperCase) If txtName.Text = "" Then MsgBox "Name field empty", vbCritical + vbOKOnly, "VALIDATION" Cancel = True ElseIf IsNumeric(txtName.Text) Then MsgBox "Only Characters are allowed", vbCritical + vbOKOnly, "ERROR" Cancel = True ElseIf Len(txtName.Text) > 20 Then MsgBox "Name exceeds 20 Characters", vbCritical + vbOKOnly, "VALIDATION" Cancel = True End If End Sub Private Sub cboDNo_Validate(Cancel As Boolean) If cboDNo.ListIndex = -1 Then MsgBox "Select the Department No.", vbCritical, "Missing data" Cancel = True End If End Sub

Step-4: Similar to "frmAddEmployee", create a new form for the Dependents and name it as

"frmDepen". The structure of the form is shown Figure 11.20. Step-5: Type the code as shown below:

Option Explicit Dim db As Connection Dim rstEmployee As Recordset Dim rstDepend As Recordset Dim rstBrowse As Recordset Private Sub cboESSN_Validate(Cancel As Boolean) If cboESSN.ListIndex = -1 Then MsgBox "Select the Employee SSN", vbCritical, "Missing data" Cancel = True End If End Sub


Fig. 11.20 Dependent Form (Arrows indicate the name of the controls)

Private Sub cboRelation_Validate(Cancel As Boolean) If cboRelation.ListIndex = -1 Then MsgBox "Select the Relationship", vbCritical, "Missing data" Cancel = True End If End Sub Private Sub cmdAdd_Click() On Error GoTo err1 rstDepend("Dependent_Name") = txtName.Text rstDepend("ESSN") = cboESSN.Text rstDepend("BDate") = txtBdate.Text rstDepend("Sex") = cboSex.Text rstDepend("Relationship") = cboRelation.Text rstDepend.Update

cboSSN

txtName

txtBDate

cboSex

cboRelation

cmdAdd

cmdCancel

DataGrid1

cboEmpSSN

cmdDelete

cmdClose

Image1

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Frame2.Enabled = True Unload Me Exit Sub err1: MsgBox Err.Description Frame2.Enabled = True End Sub Private Sub cmdCancel_Click() rstDepend.CancelUpdate Frame2.Enabled = True Frame1.Enabled = False End Sub Private Sub cmdClose_Click() Unload Me End Sub Private Sub cmdDelete_Click() On Error GoTo err1 Dim ChoiceSSN As String Dim Response As Integer Dim strSQL As String Response = MsgBox("Are you sure you want to Delete?", vbYesNo, "Confirm

Deletion") If Response = vbYes Then DataGrid1.AllowDelete = True ChoiceSSN = DataGrid1.Columns(0) strSQL = "Delete from Dependent where ESSN = " & ChoiceSSN db.Execute strSQL Call Reset DataGrid1.AllowDelete = False End If err1: MsgBox Err.Description End Sub Private Sub Form_Load() Set db = New Connection db.Open "DSN=EMPL;UID=SCOTT;PASSWORD=TIGER;" Set rstDepend = New Recordset rstDepend.CursorLocation = adUseClient rstDepend.Open "Select * from Dependent", db, adOpenDynamic, adLockOptimistic Set rstEmployee = New Recordset rstEmployee.CursorLocation = adUseClient rstEmployee.Open "Select * from Employee", db, adOpenDynamic,

adLockOptimistic 'populate the SSN combo box While Not rstEmployee.EOF cboESSN.AddItem (rstEmployee!SSN) cboEmpSSN.AddItem (rstEmployee!SSN) rstEmployee.MoveNext Wend 'Create a new empty record

rstDepend.AddNew txtName.Text = "" txtBdate.Text = "" cboESSN.Text = "Select SSN" cboRelation = "Select the Relationship" cboRelation.AddItem "Wife" cboRelation.AddItem "Husband" cboRelation.AddItem "Son" cboRelation.AddItem "Daughter" cboRelation.AddItem "Mother" cboRelation.AddItem "Father" Image1.ToolTipText = "Browse" cboSex.Text = "M" Frame2.Enabled = False End Sub Private Sub Image1_Click() If cboEmpSSN.Text <> "" Then Set rstBrowse = New Recordset rstBrowse.CursorLocation = adUseClient rstBrowse.Open "Select * from Dependent where ESSN = " & "'" &

cboEmpSSN.Text & "'", db, adOpenStatic, adLockReadOnly Set DataGrid1.DataSource = rstBrowse DataGrid1.Refresh Else MsgBox "No Employee selected", vbExclamation, "Error" End If End Sub Private Sub Reset() Set rstBrowse = New Recordset rstBrowse.CursorLocation = adUseClient rstBrowse.Open "Select * from Dependent", db, adOpenStatic, adLockReadOnly Set DataGrid1.DataSource = rstBrowse DataGrid1.Refresh End Sub Private Sub txtBdate_Validate(Cancel As Boolean) Dim UsrDate As Date Dim CurrentDate As Date UsrDate = Format(txtBdate.Text, "dd/mmm/yyyy") 'convert string to date CurrentDate = Format(Now, "dd/mmm/yyyy") 'convert string to date If UsrDate >= CurrentDate Then MsgBox "Birth date is greater than current date", vbCritical, "Error in birth date" txtBdate.SelStart = 0 txtBdate.SelLength = Len(txtBdate.Text) Cancel = True End If End Sub Private Sub txtName_Validate(Cancel As Boolean) txtName.Text = StrConv(txtName.Text, vbUpperCase) If txtName.Text = "" Then

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MsgBox "Name field empty", vbCritical + vbOKOnly, "VALIDATION" Cancel = True ElseIf IsNumeric(txtName.Text) Then MsgBox "Only Characters are allowed", vbCritical + vbOKOnly, "ERROR" Cancel = True ElseIf Len(txtName.Text) > 20 Then MsgBox "Name exceeds 20 Characters", vbCritical + vbOKOnly, "VALIDATION" Cancel = True End If End Sub

Step-6: One more work is remaining before we conclude this section. That is nothing but to

create yet another form for modifying the employee data. Hence, simply create a new form just similar to "frmAddEmployee" form. However, the code will be different for this form. You must give "frmModifyEmp" for the name property and save the form with this name. The layout is shown in Figure 11.21.

Fig. 11.21 frmModifyEmp form – to modify employee details Step-7: Type the code as given below:

Option Explicit Dim db As Connection Dim rstEmployee As Recordset Dim rstDate As Recordset Dim rstDept As Recordset Dim rstSuperSSN As Recordset


Private Sub cboSSSN_Validate(Cancel As Boolean) If cboSSSN.ListIndex = -1 Then MsgBox "You must select the supervisor" Cancel = True End If End Sub Private Sub cmdCancel_Click() Unload Me End Sub Private Sub cmdUpdate_Click() Dim strSQL As String strSQL = "Update Employee Set SSN = " & "'" & txtSSN.Text & "'" & " Where SSN =

" & "'" & frmEmployee.strSSN & "'" db.Execute strSQL strSQL = "Update Employee Set Name = " & "'" & txtName.Text & "'" & " Where SSN

= " & "'" & frmEmployee.strSSN & "'" db.Execute strSQL strSQL = "Update Employee set Address = " & "'" & txtAddr.Text & "'" & " Where

SSN = " & "'" & frmEmployee.strSSN & "'" db.Execute strSQL strSQL = "Update Employee set Sex = " & "'" & cboSex.Text & "'" & " Where SSN = "

& "'" & frmEmployee.strSSN & "'" db.Execute strSQL strSQL = "Update Employee set Salary = " & Val(txtSalary.Text) & " Where SSN = "

& "'" & frmEmployee.strSSN & "'" db.Execute strSQL strSQL = "Update Employee set SuperSSN = " & "'" & cboSSSN.Text & "'" & "

Where SSN = " & "'" & frmEmployee.strSSN & "'" db.Execute strSQL strSQL = "Update Employee set DNo = " & Val(cboDNo.Text) & " Where SSN = " &

"'" & frmEmployee.strSSN & "'" db.Execute strSQL Unload Me End Sub Private Sub Form_Load() Dim SrchSSN As String SrchSSN = frmEmployee.strSSN Set db = New Connection db.Open "DSN=EMPL;UID=SCOTT;PASSWORD=TIGER;" Set rstEmployee = New Recordset rstEmployee.CursorLocation = adUseClient rstEmployee.Open "Select * from Employee where SSN = " & "'" & SrchSSN & "'",

db, adOpenDynamic, adLockOptimistic Set rstDate = New Recordset rstDate.CursorLocation = adUseClient 'rstDate.Open "Select To_Char(BDate,'dd/mm/yyyy') as MyDate from Employee

where SSN = " & "'" & SrchSSN & "'", db, adOpenDynamic, adLockOptimistic

rstDate.Open "Select BDate from Employee where SSN = " & "'" & SrchSSN & "'", db, adOpenDynamic, adLockOptimistic

'Populate the form fields

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txtSSN.Text = rstEmployee!SSN txtName.Text = rstEmployee!Name 'Extract Day, Month, and year Dim strDOB As String strDOB = Format$(rstDate!BDate, "dd,mmm,yyyy") 'strDOB = rstDate!MyDate cboDay.Text = Left(strDOB, 2) cboMonth.Text = Mid(strDOB, 4, 3) cboYear.Text = Right(strDOB, 4) txtAddr.Text = rstEmployee!Address cboSex.Text = rstEmployee!Sex txtSalary.Text = rstEmployee!Salary cboSSSN.Text = rstEmployee!SuperSSN cboDNo.Text = rstEmployee!DNo 'populate Department Number Set rstDept = New Recordset rstDept.Open "Select DNumber from Department", db, adOpenStatic,

adLockReadOnly While Not rstDept.EOF cboDNo.AddItem rstDept!DNumber rstDept.MoveNext Wend 'populate supervisor SSN Set rstSuperSSN = New Recordset rstSuperSSN.Open "Select SSN from Employee ", db, adOpenStatic,

adLockReadOnly While Not rstSuperSSN.EOF cboSSSN.AddItem rstSuperSSN!SSN rstSuperSSN.MoveNext Wend 'Populate Day Dim intDay As Integer intDay = 1 While intDay <> 32 cboDay.AddItem intDay intDay = intDay + 1 Wend 'Populate Month cboMonth.AddItem "Jan" cboMonth.AddItem "Feb" cboMonth.AddItem "Mar" cboMonth.AddItem "Apr" cboMonth.AddItem "May" cboMonth.AddItem "Jun" cboMonth.AddItem "Jul" cboMonth.AddItem "Aug" cboMonth.AddItem "Sep" cboMonth.AddItem "Oct" cboMonth.AddItem "Nov" cboMonth.AddItem "Dec"

'Populate Year Dim intYear As Integer Dim strYear As String intYear = 1900 strYear = Right(Format(Date, "dd/mm/yyyy"), 4) While intYear <= Val(strYear) cboYear.AddItem intYear intYear = intYear + 1 Wend cboDay.Enabled = False cboMonth.Enabled = False cboYear.Enabled = False End Sub

11.4.9 Design of Department Form

The next task for our Company Database is to design the Department Form. This

time we shall present the form layout in a slightly different way. It contains just a

tool bar with five icons for Stop, New, Save, Cancel, and Delete the department

records.

Fig. 11.22 Department Form

txtDNo

txtDName

cboMSSN

txtMDate

cmdFirst cmdPrev cmdNext cmdLast

cmdCancel

cmdClose

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Give the name as "frmDept" and save the form with the same name. Now to

create the tool bar, you can follow the below steps:

Step-1: Draw an Imagelist from the tool box (left side of your main VB window). The default

name given to it will be "ImageList1". Step-2: Right lick on the ImageList1 and select properties and select the Images tab (see

Figure 11.23).

Fig. 11.23 Designing the tool bar Step-3: By clicking the "Insert Picure" button you can add any image (.ico, or .jpg, or .bmp

files). For each button, an index value is attached. This index value can be used to reference appropriate image at the time coding. The figure shows after adding the required five buttons for application.

Step-4: From the toolbox, select "Toolbar", and draw it on the form. The tool bar will look

empty. Right click on the tool bar and select properties. From the "General" tab, set the ImageList combo box to "ImageList1". Then, click on the "Buttons" tab. To add a toolbar icon, click "Insert Button" button and enter 1 in the "Image" text box (refers to the first image of the ImageList1). Similarly you can add more icons, but ensure that you fill up the Image text box with the corresponding image index (see Figure 11.24).


Fig. 11.24 Adding toolbar icons You can type relevant text in the "Tooltip Text" box. Step-5: Type the code as shown below:

Option Explicit Dim db As Connection Dim rstEmployee As Recordset Dim rstDept As Recordset Private Sub cmdCancel_Click() On Error Resume Next cboDay.Visible = False cboMonth.Visible = False cboYear.Visible = False txtMDate.Visible = True cmdFirst.Enabled = True cmdPrev.Enabled = True cmdNext.Enabled = True cmdLast.Enabled = True rstDept.CancelUpdate rstDept.CancelUpdate End Sub Private Sub cmdFirst_Click()

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On Error Resume Next rstDept.MoveFirst cmdPrev.Enabled = False cmdNext.Enabled = True End Sub Private Sub cmdLast_Click() On Error Resume Next rstDept.MoveLast cmdNext.Enabled = False cmdPrev.Enabled = True End Sub Private Sub cmdNext_Click() On Error Resume Next rstDept.MoveNext If rstDept.EOF Then rstDept.MoveLast End If cmdPrev.Enabled = True End Sub Private Sub cmdPrev_Click() On Error Resume Next rstDept.MovePrevious If rstDept.BOF Then rstDept.MoveFirst End If cmdNext.Enabled = True Exit Sub End Sub 'Dim rstBrowse As Recordset Private Sub Form_Load() Set db = New Connection db.Open "DSN=EMPL;UID=SCOTT;PASSWORD=TIGER;" Set rstDept = New Recordset rstDept.CursorLocation = adUseClient rstDept.Open "Select * from Department", db, adOpenDynamic, adLockOptimistic Set rstEmployee = New Recordset rstEmployee.CursorLocation = adUseClient rstEmployee.Open "Select * from Employee", db, adOpenDynamic,

adLockOptimistic 'populate the Manager SSN combo box While Not rstEmployee.EOF cboMSSN.AddItem (rstEmployee!SSN) rstEmployee.MoveNext Wend 'Bind the form controls to database fields Set txtDNo.DataSource = rstDept txtDNo.DataField = "DNumber" Set txtDName.DataSource = rstDept txtDName.DataField = "DName"

Set cboMSSN.DataSource = rstDept cboMSSN.DataField = "MgrSSN" Set txtMDate.DataSource = rstDept txtMDate.DataField = "MgrStartDate" 'Disable Day, Month, and Year combo boxes cboDay.Visible = False cboMonth.Visible = False cboYear.Visible = False 'Populate Day Dim intDay As Integer intDay = 1 While intDay <> 32 cboDay.AddItem intDay intDay = intDay + 1 Wend 'Populate Month cboMonth.AddItem "Jan" cboMonth.AddItem "Feb" cboMonth.AddItem "Mar" cboMonth.AddItem "Apr" cboMonth.AddItem "May" cboMonth.AddItem "Jun" cboMonth.AddItem "Jul" cboMonth.AddItem "Aug" cboMonth.AddItem "Sep" cboMonth.AddItem "Oct" cboMonth.AddItem "Nov" cboMonth.AddItem "Dec" 'Populate Year Dim intYear As Integer intYear = 2005 While intYear >= 1947 cboYear.AddItem intYear intYear = intYear - 1 Wend If rstDept.RecordCount = 0 Then MsgBox "Department Table is Empty", vbCritical, "Error" cmdFirst.Enabled = False cmdPrev.Enabled = False cmdNext.Enabled = False cmdLast.Enabled = False End If End Sub Private Sub Toolbar1_ButtonClick(ByVal Button As MSComCtlLib.Button) On Error GoTo err1 Select Case Button.Key Case "Close" Unload Me

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Case "New" rstDept.AddNew 'Create a new record and clear cmdFirst.Enabled = False cmdPrev.Enabled = False cmdNext.Enabled = False cmdLast.Enabled = False txtMDate.Visible = False cboDay.Visible = True cboMonth.Visible = True cboYear.Visible = True txtDNo.Text = "" txtDName.Text = "" cboMSSN.Text = "" cboDay.Text = "" cboMonth.Text = "" cboYear.Text = "" txtDNo.SetFocus Case "Save" 'On Error GoTo err1 Dim strDate As String rstDept!DNumber = txtDNo.Text rstDept!DName = txtDName.Text If cboMSSN.Text = "" Then rstDept!MgrSSN = Null Else rstDept!MgrSSN = cboMSSN.Text End If strDate = cboDay.Text + "/" + cboMonth.Text + "/" + cboYear.Text rstDept!MgrStartDate = strDate rstDept.Update cmdFirst.Enabled = True cmdPrev.Enabled = True cmdNext.Enabled = True cmdLast.Enabled = True cboDay.Visible = False cboMonth.Visible = False cboYear.Visible = False txtMDate.Visible = True rstDept.Requery Case "Undo" cmdCancel_Click Case "Delete" On Error Resume Next Dim intChoice If Not txtDNo = "" Then If Not rstDept.EOF Then intChoice = MsgBox("Are you sure that you want to delete?", vbYesNo +

vbCritical) If intChoice = vbYes Then rstDept.Delete rstDept.MoveNext If rstDept.EOF Then


rstDept.MoveLast End If End If End If Else MsgBox "No Record to Delete", vbExclamation End If End Select Exit Sub err1: MsgBox Err.Description End Sub Private Sub cmdClose_Click() Unload Me End Sub

11.4.10 Design of Project Form

The Project form can be designed exactly same as the previous form, except for

changes in the labels. Therefore, we will not give the details for this form but only

the code (see Figure 11.25).

Option Explicit Dim db As Connection Dim rstProject As Recordset Dim rstDept As Recordset

Private Sub cmdCancel_Click() cmdFirst.Enabled = True cmdPrev.Enabled = True cmdNext.Enabled = True cmdLast.Enabled = True Toolbar1.Buttons.Item(2).Enabled = True Toolbar1.Buttons.Item(5).Enabled = True rstProject.CancelUpdate End Sub Private Sub cmdFirst_Click() On Error Resume Next rstProject.MoveFirst cmdPrev.Enabled = False cmdNext.Enabled = True End Sub Private Sub cmdLast_Click() On Error Resume Next rstProject.MoveLast cmdNext.Enabled = False cmdPrev.Enabled = True End Sub

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Private Sub cmdNext_Click() On Error Resume Next rstProject.MoveNext If rstProject.EOF Then rstProject.MoveLast End If cmdPrev.Enabled = True End Sub

Fig. 11.25 Project Form (frmProject)

Private Sub cmdPrev_Click() On Error Resume Next rstProject.MovePrevious If rstProject.BOF Then rstProject.MoveFirst End If cmdNext.Enabled = True Exit Sub End Sub Private Sub Form_Load() Set db = New adodb.Connection db.Open "DSN=EMPL;UID=SCOTT;PASSWORD=TIGER;" Set rstProject = New Recordset rstProject.CursorLocation = adUseClient rstProject.Open "Select * from Project", db, adOpenDynamic, adLockOptimistic


Set rstDept = New Recordset rstDept.CursorLocation = adUseClient rstDept.Open "Select * from Department", db, adOpenDynamic, adLockOptimistic 'populate the Dept Number combo box While Not rstDept.EOF cboDNum.AddItem (rstDept!DNumber) rstDept.MoveNext Wend 'Bind the form controls to database fields Set txtPNo.DataSource = rstProject txtPNo.DataField = "PNumber" Set txtPName.DataSource = rstProject txtPName.DataField = "PName" Set cboPLoc.DataSource = rstProject cboPLoc.DataField = "PLocation" Set cboDNum.DataSource = rstProject cboDNum.DataField = "DNum" 'populate Project locations combo box cboPLoc.AddItem "Bangalore" cboPLoc.AddItem "Chennai" cboPLoc.AddItem "New Delhi" cboPLoc.AddItem "Mumbai" cboPLoc.AddItem "Kolkota" cboPLoc.AddItem "Coimbatore" cboPLoc.AddItem "Pune" cboPLoc.AddItem "Belgaum" cboPLoc.AddItem "Mysore" End Sub Private Sub Toolbar1_ButtonClick(ByVal Button As MSComCtlLib.Button) On Error GoTo err1 Select Case Button.Key Case "Close" Unload Me Case "New" rstProject.AddNew 'Create a new record and clear cmdFirst.Enabled = False cmdPrev.Enabled = False cmdNext.Enabled = False cmdLast.Enabled = False txtPNo.Text = "" txtPName.Text = "" cboPLoc = "" cboDNum.Text = "" txtPNo.SetFocus 'disable New button and Delete button Toolbar1.Buttons.Item(2).Enabled = False Toolbar1.Buttons.Item(5).Enabled = False

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Case "Save" On Error GoTo err1 rstProject!PNumber = Val(txtPNo.Text) rstProject!PName = txtPName.Text rstProject!PLocation = cboPLoc.Text rstProject!DNum = cboDNum.Text rstProject.Update cmdFirst.Enabled = True cmdPrev.Enabled = True cmdNext.Enabled = True cmdLast.Enabled = True rstProject.Requery Toolbar1.Buttons.Item(2).Enabled = True Toolbar1.Buttons.Item(5).Enabled = True Case "Undo" cmdCancel_Click Case "Delete" On Error Resume Next Dim intChoice If Not rstProject.EOF Then intChoice = MsgBox("Are you sure that you want to delete?", vbYesNo +

vbCritical) If intChoice = vbYes Then rstProject.Delete rstProject.MoveNext If rstProject.EOF Then rstProject.MoveLast End If End If End If End Select Exit Sub err1: MsgBox "The following Error has occured: " + Err.Description End Sub Private Sub cmdClose_Click() Unload Me End Sub Private Sub txtPNo_KeyPress(KeyAscii As Integer) If KeyAscii < Asc("0") Or KeyAscii > Asc("9") Then KeyAscii = 0 End If End Sub

11.4.11 Design of Department Locations Form

We shall adopt a unique technique to design this form. The requirement for this

form is that we must get the department number and the locations. For each

department, we may have one or more locations. Instead of adding individual


records, we shall use a FlexGrid to obtain all the records (maximum is say 3) and

save together in the database.

Step-1: Go to Project > Add Form > Form, then click Open. Step-2: Draw the controls as indicated in the Figure 11.26. Control Name Caption Frame Frame1 Dept and Locations Combo Box cboDeptNo - Combo Box cboDeptLoc - Command Button cmdAdd Add Frame Frame2 Records MSFlexGrid Grid1 - Command Button cmdSave Save Command Button cmdCancel Cancel

Fig. 11.26 frmDeptLoc Form

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To add the FlexGrid control to the toolbox, click Ctrl+T and select Microsoft FlexGrid Control 6.0) and press "OK". Step-3: Type the following program, for each control shown in the above figure.

Option Explicit Dim db As Connection Dim rstTemp As Recordset Dim rstDept As Recordset

Private Sub cmdAdd_Click() Dim row As Integer If cboDeptNo.ListIndex <> -1 And cboDeptLoc.ListIndex <> -1 Then row = Grid1.Rows - 1 Grid1.TextMatrix(row, 0) = row Grid1.TextMatrix(row, 1) = cboDeptNo.Text Grid1.TextMatrix(row, 2) = cboDeptLoc.Text Grid1.Rows = Grid1.Rows + 1 cboDeptNo.Text = "" cboDeptLoc.Text = "" cboDeptNo.SetFocus Else MsgBox "No data in the Fields" & Chr(13) + Chr(10) & "Select Dept. No and

Location" cboDeptNo.SetFocus End If End Sub Private Sub cmdCancel_Click() Unload Me End Sub Private Sub cmdSave_Click() Dim i As Integer 'whole grid is empty If Grid1.Rows < 3 Then MsgBox "There is no record to save" Exit Sub End If On Error GoTo DatabaseError 'start saving Set rstTemp = New Recordset rstTemp.Open "select * from Dept_Locations", db, adOpenDynamic,

adLockOptimistic 'start transaction db.BeginTrans For i = 1 To Grid1.Rows - 2 rstTemp.AddNew rstTemp.Fields("DNumber") = Val(Grid1.TextMatrix(i, 1)) rstTemp.Fields("DLocation") = Grid1.TextMatrix(i, 2) rstTemp.Update Next i 'commit transaction to save changes db.CommitTrans

MsgBox "The data has been saved successfully", vbInformation, "FMC United" Grid1.Clear Call InitGrid cboDeptNo.SetFocus Exit Sub DatabaseError: db.RollbackTrans MsgBox "The following error has occured while saving data : " & Chr(13) +

Chr(10) & " No : " & Err.Number & " Description : " & Err.Description Grid1.Clear Call InitGrid cboDeptNo.SetFocus End Sub Private Sub Form_Load() Call InitGrid Set db = New Connection db.Open "DSN=EMPL;UID=SCOTT;PASSWORD=TIGER;" Set rstDept = New Recordset rstDept.CursorLocation = adUseClient rstDept.Open "Select * from Department", db, adOpenDynamic, adLockOptimistic 'populate the dept. no. combo box While Not rstDept.EOF cboDeptNo.AddItem (rstDept!DNumber) rstDept.MoveNext Wend 'populate dept. locations combo box cboDeptLoc.AddItem "Bangalore" cboDeptLoc.AddItem "Chennai" cboDeptLoc.AddItem "New Delhi" cboDeptLoc.AddItem "Mumbai" cboDeptLoc.AddItem "Kolkota" cboDeptLoc.AddItem "Coimbatore" cboDeptLoc.AddItem "Pune" cboDeptLoc.AddItem "Belgaum" cboDeptLoc.AddItem "Mysore" End Sub Public Sub InitGrid() Dim s As String Grid1.BackColorFixed = vbCyan s$ = "<SR_NO|Dept. No.|Dept. Locations" Grid1.FormatString = s$ Grid1.ColWidth(1) = 1200 Grid1.ColWidth(2) = 2000

Grid1.Rows = 2 End Sub

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11.4.12 Design of Employee Work Details

To populate the Works_On table, we need a form. Let us call this form as

"frmWorks". We select the SSN and the Project No from the combo boxes; then

enter the number of hours an employee worked on this project. When you save the

record, you automatically get the table updated; that is, shown in the DataGrid.

With these requirements in mind, the Works form will look like the one shown in

Figure 11.27.

Step-1: Add a new form and draw the controls. Control Name Caption Frame Frame1 Work Details Combo Box cboESSN - Combo Box cboPNo - Command Button cmdNew New Command Button cmdSave Save Frame Frame2 Employee Work table DataGrid DataGrid1 - Command Button cmdDelete Delete Command Button cmdCancel Cancel Step-2: Note that to modify the properties of the DataGrid, right click on the DataGrid and

select properties. Save the form as "frmWorks". Step-3: Type the code as shown below:

Option Explicit Dim db As Connection Dim rstWorks As Recordset Dim rstEmployee As Recordset Dim rstProject As Recordset Dim rstTemp As Recordset Private Sub cmdCancel_Click() Unload Me End Sub


Fig. 11.27 Employee Work Form (frmWorks)

Private Sub cmdDelete_Click() On Error GoTo err1 Dim ChoiceSSN As String Dim Response As Integer Dim strSQL As String Response = MsgBox("Are you sure you want to Delete?", vbYesNo, "Confirm

Deletion") If Response = vbYes Then DataGrid1.AllowDelete = True ChoiceSSN = DataGrid1.Columns(0) strSQL = "Delete from Works_On where ESSN = " & ChoiceSSN db.Execute strSQL Call Reset DataGrid1.AllowDelete = False End If Exit Sub err1: MsgBox Err.Description End Sub Private Sub cmdNew_Click() cmdNew.Enabled = False cboESSN.Enabled = True cboPNo.Enabled = True txtHours.Enabled = True cmdSave.Enabled = True cboESSN.Text = "" cboPNo.Text = ""

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txtHours.Text = "" rstWorks.AddNew End Sub Private Sub cmdSave_Click() On Error GoTo err1 rstWorks!ESSN = cboESSN.Text rstWorks!PNo = cboPNo.Text rstWorks!Hours = txtHours.Text rstWorks.Update Call Reset cboESSN.Enabled = False cboPNo.Enabled = False txtHours.Enabled = False cmdSave.Enabled = False cmdNew.Enabled = True Exit Sub err1: MsgBox Err.Description End Sub Private Sub Form_Load() Set db = New adodb.Connection db.Open "DSN=EMPL;UID=SCOTT;PASSWORD=TIGER;" Set rstWorks = New Recordset rstWorks.CursorLocation = adUseClient rstWorks.Open "Select * from Works_On", db, adOpenDynamic, adLockOptimistic Set rstEmployee = New Recordset rstEmployee.CursorLocation = adUseClient rstEmployee.Open "Select * from Employee", db, adOpenStatic, adLockReadOnly Set rstProject = New Recordset rstProject.CursorLocation = adUseClient rstProject.Open "Select * from Project", db, adOpenStatic, adLockReadOnly 'populate the ESSN combo box While Not rstEmployee.EOF cboESSN.AddItem (rstEmployee!SSN) rstEmployee.MoveNext Wend 'populate the PNo combo box While Not rstProject.EOF cboPNo.AddItem (rstProject!PNumber) rstProject.MoveNext Wend cboESSN.Enabled = False cboPNo.Enabled = False txtHours.Enabled = False cmdSave.Enabled = False Call Reset End Sub Private Sub Reset() Set rstTemp = New Recordset


rstTemp.CursorLocation = adUseClient rstTemp.Open "Select * from Works_on order by ESSN", db, adOpenStatic,

adLockReadOnly Set DataGrid1.DataSource = rstTemp DataGrid1.Refresh End Sub

11.4.13 Design of Help Menu (Technical Form and About Form)

You might have noticed that there are two submenu items in the "Help" menu. The

first one is "Technical Support" and the second is "About". To design the first form,

we need just a multi-line text box and "OK" button. So it becomes very easy. Look

at the Figure 11.28.

Fig. 11.28 Help menu design (frmTechnical) Step-1: Add a new form with name "frmTechnical" and save the form with the same name. Step-2: Draw a text box with name "txtName" and set its Multiline property to "true". You will

see a scroll bar attached automatically at design time and also at run time. Step-3: Draw a Command Button called "cmdOK" with its caption property set to "OK". Step-4: Type the following code: Private Sub Form_Load() txtHelp.Text = "1. First enter all the divisions: " + Chr(13) + Chr(10) + "Department, Employee,

Dependents, Project, etc. You must follow the same order." + Chr(13) + Chr(10) + Chr(13) + Chr(10) + _

"2. The Reports menu generates various reports like Employee details, Department details, etc." + Chr(13) + Chr(10) + Chr(13) + Chr(10) + _

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"3. You can search for an employee by giving SSN or Name." + Chr(13) + Chr(10) + Chr(13) + Chr(10) + _

"4. If you want to login as a different user, select File menu and click Login." End Sub Private Sub OKButton_Click() Unload Me End Sub Step-5: To design the "About" form, go to Project > Add Form and then select "About Dialog". Step-6: Save the form as "frmAbout". Step-7: You don't need to type any code for this form as VB automatically puts the code for

you. However, to customize for our application, modify the Form_Load section only as shown below:

Private Sub Form_Load() Me.Caption = "About Company Database" lblVersion.Caption = "Version " & App.Major & "." & App.Minor & "." & App.Revision End Sub

The form is shown in Figure 11.29.

Fig. 11.29 Design of About form ("frmAbout")

This completes the design of main forms. The next section would describe the

details of Report generation.


11.5 REPORT GENERATION

Without useful reports from the database, our application is incomplete. Hence, let

us explain the steps needed to design VB reports for the Company database. Let us

design few simple reports, but show the steps in detail. To design reports in VB do

the following steps:

Step-1: Go to Project > Add data Environment. You will see a default data environment by

name "Data Environment1" and a default connection "Connection1" (see Figure 11.30).

Step-2: Right click on "Connection1" and select "Add Command". By doing this you will get a

default command called "Command1". You can change the names of these controls by going to the properties menu. For our application change the name of the command to "cmdEmployee"

Step-3: Right click on the "cmdEmployee" and select the properties. You will see a new

window and check the SQL Statement. Type the SQL statement as shown in Figure 11.31 and click "OK" button.

Fig. 11.30 Creating Data Environment

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Fig. 11.31 Query statement for Employee report Step-4: Similarly, create four more commands by right clicking the "Connection1". Give the

names as "cmdDependents", "cmdWages", "cmdProject", "cmdDept". Type the code for each of these commands as shown below. See Figures 11.32.

Code for "cmdDependents": Select * from Dependent where ESSN = ? Code for "cmdWages": Select SSN, Name, TotalHrs, TotalHrs * ? from Employee, SSNHrs where SSN =

ESSN Code for "cmdProject" Select PNumber, PName, PLocation, DName from Project, Department where

Project.DNum = DNumber Code for "cmdDept": Select D.DName, E.Name, D.MgrStartDate, DL.DLocation from Employee E,

Department D, Dept_Locations DL where E.SSN = D.MgrSSN and D.DNumber = DL.DNumber order by D.DName

The ? indicates the parameter which will be sent when the command is invoked.


Fig. 11.32 Creation of "Commands" Step-5: The next step is to design the layout for the reports. Click on Project > Add Data

Report. You will see a default data report called "Datareport1" created. Rename it as "rptEmployee".

Step-6: Change the name property to "Employee Details". Firstly, select the data report

window. Next, click on the Data Source property and select "Data Environment1". Finally, select the Data Member property and select the appropriate command. In this case, click on "cmdEmployee" (See Figure 11.33).

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Fig. 11.33 Designing Data Report Step-7: Right Click on the Detail Section > Insert Control > Textbox. Select Data Member

property and select "cmdEmployee". Next, you must select Data member property and click the appropriate field. Continue this process until you create textboxes for all the fields. Create labels wherever required. Recall that the textboxes in the "Detail" section will be filled by all the records of the table.

Step-8: Repeat Steps-5 to Step-7 for the remaining commands. The reports for Employee and

Department at run time are shown in Figure 11.34.


Fig. 11.34 Employee Report

This completes the entire design of the Company Database. You can now test

the application by entering sample data and generate few reports. To receive the

soft copy, please send an e-mail to the author ([email protected]).

11.6ADDITIONAL EXAMPLES

This section discusses some more database problems and their solutions using SQL

statements. A number of exercise problems for designing VB forms and reports are

given at the end of this chapter. Readers are encouraged to solve these problems to

get better understanding of the application development.

11.6.1 Insurance Database

Consider the Insurance database given below. The primary keys are underlined

and the data types are specified.

PERSON (Driverid# : String, Name : String, Address : String)

CAR (RegNo : String, Model : String, Year : Int)

ACCIDENT (ReportNo : Int, AccDate : Date, Location : String)

OWNS (Driverid# : String, RegNo : String)

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PARTICIPATED (Driverid# : String, RegNo : String, ReportNo : Int, DamageAmount : Int)

(a) Create the above tables by specifying the primary keys and foreign keys. (b) Enter at least five tuples for each relation. (c) Demonstrate how you i) update the damage amount for the car with a specific RegNo in the accident with ReportNo 12 to 25000. (d) Find the total number of people who owned cars that were involved in accidents in 2002. (e) Find the number of accidents in which cars belonging to a specific model were involved. Solution

(a) create table Person( Driverid# varchar2(5), Name varchar2(15) not Null, Address varchar2(20), primary key (Driverid#)); create table Car( RegNo varchar2(9), Model varchar2(15) not Null, Year integer not Null, primary key (RegNo)); create table Accident( ReportNo Integer, AccDate Date not Null, Location varchar2(15) not Null, primary key (ReportNo)); create table Owns( Driverid# varchar2(5), RegNo varchar2(9), primary key (Driverid#, RegNo), foreign key (Driverid#) references Person(Driverid#), foreign key (RegNo) references Car(RegNo)); create table Participated( Driverid# varchar2(5), RegNo varchar2(9),ReportNo Integer, DamageAmount integer, primary key (Driverid#, RegNo, ReportNo), foreign key (Driverid#) references Person(Driverid#), foreign key (RegNo) references Car(RegNo), foreign key (ReportNo) references Accident(ReportNo)); (b) Insert into Person values('1111', 'Ramu', 'K. S. Layout'); Insert into Person values('2222', 'Michel', 'Indiranagar'); Insert into Person values('3333', 'Priya', 'Rajajinagar'); Insert into Person values('4444', 'Gopal', 'Whitefield'); Insert into Person values('5555', 'Latha', 'Indiranagar'); Insert into Car values('KA04Q2301', 'MARUTHI-DX', 2000); Insert into Car values('KA05P1000', 'FORD IKON', 2002); Insert into Car values('KA03L1234', 'ZEN-VXI', 1999); Insert into Car values('KA03L9999', 'MARUTHI-STD', 2000); Insert into Car values('KA01P4028', 'INDICA-VX', 2004); Insert into Accident values(12, '01-JUN-2002', 'M G ROAD'); Insert into Accident values(200, '10-DEC-2002', 'DOUBLE ROAD'); Insert into Accident values(300, '23-JUL-1999', 'M G ROAD'); Insert into Accident values(25000, '11-JAN-2000', 'RESIDENCY ROAD'); Insert into Accident values(26500, '16-OCT-2001', 'RICHMOND ROAD');


Insert into Owns values('1111', 'KA04Q2301'); Insert into Owns values('1111', 'KA05P1000'); Insert into Owns values('2222', 'KA03L1234'); Insert into Owns values('3333', 'KA03L9999'); Insert into Owns values('4444', 'KA01P4028'); Insert into Participated values('1111', 'KA04Q2301', 12, 20000); Insert into Participated values('2222', 'KA03L1234', 200, 500); Insert into Participated values('3333', 'KA03L9999', 300, 10000); Insert into Participated values('4444', 'KA01P4028', 25000, 2375); Insert into Participated values('1111', 'KA05P1000', 26500, 70000); (c) update Participated set damageamount = 1111 where RegNo = 'KA01P4028' and ReportNo between 12 and 25000; insert into Accident values (31000, '3-Jan-2004', 'Wilson Garden'); insert into Participated values ('3333','KA03L9999', 31000, 5400); (d) SELECT COUNT(*) FROM ACCIDENT WHERE ACCDATE LIKE '__-___-02'; (e) Select count(*) from Car C, Participated P where C.RegNo = P.RegNo and Model = 'MARUTHI-DX';

11.6.2 Order Processing Database

Consider the Order Processing database given below. The primary keys are

underlined and the data types are specified.

CUSTOMER (Cust# : Int, CName : String, City : String)

CUSTORDER (Order# : Int, ODate : Date, Cust# : Int, OrdAmt : Int)

ORDER_ITEM (Order# : Int, Item# : Int, Qty : Int)

SHIPMENT (Order# : Int, Warehouse# : Int, Shipdate : Date)

WAREHOUSE (Warehouse# : Int, City : String)

(a) Create the above tables by specifying the primary keys and foreign keys. (b) Enter at least five tuples for each relation. (c) Produce a listing: CustName, #ofOrders, Avg_Order_Amt, where the middle column is the total number of orders made by the customer and the last column is the average order amount for that customer. (d) List the order# for orders that were shipped from all the warehouses that the company has in a specific city. (e) Demonstrate how you delete item# 10 from ITEM table and make that field null in the ORDER_ITEM table.

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Solution

(a) Create table Customer( Cust# integer, CName varchar2(15) not Null, City varchar2(15), primary key (Cust#)); Create table CustOrder( Order# integer, ODate date not Null, Cust# integer, OrdAmt integer not Null, primary key (Order#), foreign key (Cust#) references Customer(Cust#)); Create table Item( Item# integer, Unitprice integer not Null, primary key (Item#)); Create table Order_Item( Order# integer, Item# integer, Qty integer, primary key (Order#, Item#), foreign key (Order#) references CustOrder(Order#), foreign key (Item#) references Item(Item#)); Create table Warehouse( Warehouse# integer, City varchar2(15) not Null, primary key (Warehouse#)); Create table Shipment( Order# integer, Warehouse# integer, Shipdate date, primary key (Order#, Warehouse#), foreign key (Order#) references CustOrder(Order#), foreign key (Warehouse#) references Warehouse(Warehouse#)); (b) Insert into Customer values (1111, 'Gupta', 'Bangalore'); Insert into Customer values (2222, 'Deepali', 'Mangalore'); Insert into Customer values (3333, 'Kiran', 'Chennai'); Insert into Customer values (4444, 'John', 'Bangalore'); Insert into Customer values (5555, 'Abbas', 'Belgaum'); Insert into CustOrder values (100, '01-JUN-2004', 1111, 10000); Insert into CustOrder values (200, '11-JUL-2004', 2222, 20000); Insert into CustOrder values (300, '21-DEC-2003', 3333, 30000); Insert into CustOrder values (400, '17-JUN-2004', 4444, 40000); Insert into CustOrder values (500, '11-JUL-2004', 2222, 50000); Insert into Item values (10, 500); Insert into Item values (20, 250); Insert into Item values (30, 100); Insert into Item values (40, 5); Insert into Item values (50, 5); Insert into Order_Item values (100, 10, 3); Insert into Order_Item values (200, 20, 10); Insert into Order_Item values (300, 10, 7); Insert into Order_Item values (400, 30, 3); Insert into Order_Item values (500, 40, 20);


Insert into Warehouse values (1, 'Coimbatore'); Insert into Warehouse values (2, 'Pune'); Insert into Warehouse values (3, 'Cochin'); Insert into Warehouse values (4, 'Bangalore'); Insert into Warehouse values (5, 'Bangalore'); Insert into Shipment values (100, 1, '02-JAN-2002'); Insert into Shipment values (200, 2, '02-JAN-2002'); Insert into Shipment values (300, 3, '12-DEC-2001'); Insert into Shipment values (400, 4, '30-MAR-2004'); Insert into Shipment values (500, 4, '09-AUG-2000'); insert into shipment values(100, 5, '09-APR-2002'); (c) Select C.CName, count(CO.Order#), Avg(CO.OrdAmt) from Customer C, CustOrder CO where C.Cust# = CO.Cust# group by C.CName, CO.Cust#; (d) Select Order#, Warehouse# from Shipment where warehouse# in (select warehouse# from warehouse where City = 'Bangalore'); (e) Delete from Item where Item# = 10 and (update Order_Item set Item# = Null where Item# = 10);

11.6.3 Student Enrollment Database

Consider the Student Enrollment database given below. The primary keys are

underlined and the data types are specified.

STUDENT (RegNo : String, Name : String, Major : String, BDate : date)

COURSE (Course# : Int, CName : String, Dept : String)

ENROLL (RegNo : String, Course# : Int, Sem : Int, Marks : Int)

BOOK_ADOPTION (Course# : Int, Sem : Int, ISBN : Int)

TEXT (ISBN : Int, BookTitle : String, Publisher : String, Author : String)

(a) Create the above tables by specifying the primary keys and foreign keys. (b) Enter at least five tuples for each relation. (c) Produce a list of text books (include Course#, ISBN, BookTitle) in the alphabetical order for courses offered by the 'CS' department that use more than two books. Solution

(a) create table Student( RegNo varchar2(10), Name varchar2(20) not null, Major varchar2(10) not null, BDate date, primary key(RegNo));

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create table Course( Course# integer, CName varchar2(15) not null, Dept varchar2(10) not null, primary key(Course#)); create table Enroll( RegNo varchar2(10), Course# integer, Sem integer not null, Marks integer, primary key(RegNo, Course#), foreign key (RegNo) references Student(RegNo), foreign key (Course#) references Course(Course#)); create table Text( ISBN integer, BookTitle varchar2(20) not null, Publisher varchar2(20), Author varchar2(15), primary key(ISBN)); create table Book_Adoption( Course# integer, Sem integer, ISBN integer, primary key(Course#, Sem), foreign key (Course#) references Course(Course#), foreign key (ISBN) references Text(ISBN)); (b) Insert into Student values('1BI00CS010', 'KIRAN', 'CSE', '02-JAN-1983'); Insert into Student values('1BI01ME075', 'DIVYA', 'MECH', '10-DEC-1984'); Insert into Student values('1BI02EC041', 'DIWAKAR', 'ELNS', '22-FEB-1984'); Insert into Student values('1BI00CS035', 'JOHN', 'CSE', '23-MAR-1982'); Insert into Student values('1BI03CS010', 'MUKUND', 'CSE', '15-AUG-1983'); Insert into Course values(11, 'DSC', 'CSE'); Insert into Course values(22, 'ADA', 'CSE'); Insert into Course values(33, 'CN', 'EC'); Insert into Course values(44, 'TD', 'MECH'); Insert into Course values(55, 'MuP', 'EC'); Insert into Enroll values('1BI00CS010', 22, 5, 72); Insert into Enroll values('1BI00CS010', 11, 3, 90); Insert into Enroll values('1BI02EC041', 33, 6, 52); Insert into Enroll values('1BI01ME075', 44, 4, 85); Insert into Enroll values('1BI00CS035', 22, 5, 75); Insert into Book_Adoption values(11, 3, 7722); Insert into Book_Adoption values(22, 4, 7722); Insert into Book_Adoption values(11, 5, 4400); Insert into Book_Adoption values(11, 8, 5566); Insert into Book_Adoption values(55, 4, 3388); Insert into Book_Adoption values(44, 4, 5566); Insert into Book_Adoption values(44, 7, 3388); Insert into Text values(7722, 'VB6', 'Dreamtech', 'Holzner'); Insert into Text values(1144, 'DS WITH C', 'Sapna', 'Nandagopal'); Insert into Text values(4400, 'C Programming', 'TMH', 'Balagurusamy'); Insert into Text values(5566, 'Computer NW', 'PHI', 'Tennenbaum'); Insert into Text values(3388, 'MuP', 'PHI', 'Brey');


(c) Select C.Course#, T.ISBN, T.BookTitle from Course C,Book_Adoption BA, Text T where C.Course# = BA.Course# and BA.ISBN = T.ISBN and C.Dept = 'CSE' group by C.Course#, T.ISBN, T.BookTitle;

11.6.4 Book Dealer Database

Consider the Book dealer database given below. The primary keys are underlined

and the data types too are specified.

AUTHOR (Authorid : Int, Name : String, City : String, Country : String)

PUBLISHER (Publisherid : Int, Name : String, City : String, Country : String)

CATALOG (Bookid : Int, Title : String, Authorid : Int, Publisherid : Int, Categoryid : Int, Year : Int, Price : Int)

CATEGORY (Categorid : Int, Description : String)

ORDER_DETAILS (OrderNo : Int, Bookid : Int, Quantity : Int)

(a) Create the above tables by specifying the primary keys and foreign keys. (b) Enter at least five tuples for each relation. (c) Give the details of the authors who have 2 or more books in the catalog and the proce of the books is greater than the average price of the books in the catalog and the year of publication is after 2000. (d) Find the number of the book which has maximum sales. (e) Demonstrate how you increase the price of books published by a specific publisher by 10%. Solution

(a) Create table Author( Authorid integer, AName varchar2(15), ACity varchar2(15), ACountry varchar2(15), primary key (Authorid)); Create table Publisher( Publisherid integer, PName varchar2(15), PCity varchar2(15), PCountry varchar2(15), primary key (Publisherid)); Create table Category( Categoryid integer, Description varchar2(20), primary key(Categoryid)); Create table Catalog( Bookid integer, Title varchar2(20), Authorid integer, Publisherid integer, Categoryid integer, Year integer, Price integer, primary key (Bookid), Foreign key (Authorid) references Author(Authorid), Foreign key (Publisherid) references Publisher(Publisherid), Foreign key (Categoryid) references Category(Categoryid)); Create table Order_Details( OrderNo integer, Bookid integer, Quantity integer, primary key (OrderNo, Bookid),

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Foreign key (bookid) references catalog(Bookid)); (b) Insert into Author values(1000, 'Nandagopalan', 'Bangalore', 'India'); Insert into Author values(2000, 'Tony', 'Haywood', 'USA'); Insert into Author values(3000, 'Holzner', 'New York', 'USA'); Insert into Author values(4000, 'Tennenbaum', 'London', 'UK'); Insert into Author values(5000, 'Balaguruswamy', 'Chennai', 'India'); Insert into Publisher values(11, 'Wiely', 'New Delhi', 'India'); Insert into Publisher values(22, 'PHI', 'California', 'USA'); Insert into Publisher values(33, 'Sapna', 'Bangalore', 'India'); Insert into Publisher values(44, 'TMH', 'New York', 'USA'); Insert into Publisher values(55, 'Wrox', 'Texas', 'USA'); Insert into Category values(1, 'OS'); Insert into Category values(2, 'Languages'); Insert into Category values(3, 'Hardware'); Insert into Category values(4, 'Algorithms'); Insert into Category values(5, 'Internet'); Insert into Catalog values(123, 'DSC', 1000, 33, 2, 2000, 185); Insert into Catalog values(456, 'Networks', 4000, 44, 4, 2002, 365); Insert into Catalog values(789, 'VB6', 2000, 11, 2, 2000, 300); Insert into Catalog values(213, 'Frontpage2002', 4000, 44, 5, 2003, 500); Insert into Catalog values(879, 'ADA', 1000, 33, 4, 2001, 195); Insert into Order_Details values(112, 123, 100); Insert into Order_Details values(113, 123, 20); Insert into Order_Details values(114, 213, 50); Insert into Order_Details values(115, 789, 500); Insert into Order_Details values(116, 879,8); (c) select C.Authorid, A.AName from Catalog C, Author A where A.Authorid = C.Authorid and C.Year > 2000 and C.Price > (Select Avg(Price) from Catalog) group by C.Authorid, A.AName having count(C.Authorid) >= 2; (d) Create View SalesDetails as ( Select OD.Bookid as Book#, C.Price as Cost, Sum(OD.Quantity) as Qty, Sum(OD.Quantity *

C.Price) as Sales from Order_Details OD, Catalog C, Author A where OD.Bookid = C.Bookid and C.Authorid = A.Authorid group by OD.Bookid, C.Price); select A.Authorid, A.AName,S.book#, S.Sales from Author A, catalog C, Salesdetails S where A.Authorid = C.Authorid and S.Book# = C.Bookid and sales = ( select Max(Sales) from salesdetails); (e) update Catalog set Price = Price * 1.10


where Publisherid = 33;

11.6.5 Bank Database

You will understand, in this section, an application that is developed using Oracle

9i and VB 6.0 to maintain bank accounts and loan details of customers. Fisrt of all,

assume that the following tables are given to us:

BRANCH (Branch_Name : String, Branch_City : String, Assets : Real)

ACCOUNT (AccNo : Integer, Branch_Name : String, Balance : Real)

DEPOSITOR (Customer_Name : String, AccNo : Integer)

CUSTOMER (Customer_Name : String, Customer_Street : String, Customer _City : String)

LOAN (Loan_Number : Integer, Branch_Name : String, Amount : Real) BORROWER (Customer_Name : String, Loan_Number : Integer)

The development process is same as what we have shown already in previous

sections. Therefore, without explaining further the general menu structure may be

designed as shown in Figure 11.37.

In this application, the main menu items and sub menu items are arranged

differently compared to the other applications. For example, from the main menu

the users can navigate to open a Branch, or open a new Customer, or open a new

Loan, etc. They can also enquire about Branches, or Accounts, or Balance amount of

any account type. The Reports Menu is not filled with any specific details and is

left to the reader to design relevant reports. Keeping these requirements, let us

design the menu and is shown in Figure 11.38.

Branch Customer Account Loan Enquiry Reports Help

New New New New Branch Technical

Existing Existing Existing Existing Customer About

Delete Delete Delete Delete Account

Exit Loan

Balance

Fig. 11.37 Menu Structure of Bank Database

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Fig. 11.38 The Main Menu

Similarly, the other forms BranchNew, BranchExisiting, and BranchDel are

shown in Figures 11.39 to 11.41.

Fig. 11.39 BranchNew Form


Fig. 11.40 BranchExisting Form

Fig. 11.41 BranchDel Form

Now, the VB codes for all the above forms appear in the next page:

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Code for Main Form

Private Sub mnuBrDelete_Click() BranchDel.Show vbModal End Sub Private Sub mnuBrExisting_Click() BranchExisting.Show End Sub Private Sub mnuBrNew_Click() BranchNew.Show vbModal End Sub Private Sub mnuExit_Click() End End Sub

Code for BranchNew Form

Option Explicit Dim DB As Connection Dim rstBranch As Recordset Private Sub cmdCancel_Click() Unload Me End Sub Private Sub cmdSubmit_Click() On Error GoTo Err Dim intFlag As Integer intFlag = 0 If txtBrName.Text = "" Then MsgBox "Branch Name is empty" intFlag = 1 End If If cboBrCity.ListIndex = -1 Then MsgBox "Branch City is empty" intFlag = 1 End If If txtAssets.Text = "" Then MsgBox "Assets is empty" intFlag = 1 End If If intFlag = 0 Then rstBranch!branchname = txtBrName.Text rstBranch!branchcity = cboBrCity.Text rstBranch!assets = txtAssets.Text rstBranch.Update MsgBox "Record saved successfully", vbInformation, "Save Status" Unload Me End If Exit Sub Err: If Err.Number = -2147217873 Then 'Violation of primary key constraint MsgBox "Duplicate Branch Name", vbCritical, "Error"


End If End Sub Private Sub Form_Load() 'On Error Resume Next 'Create connection object (for Oracle database) Set DB = New Connection DB.Open "DSN=Elective;UID=Prob5;PASSWORD=Prob5" 'Create recordset object Set rstBranch = New Recordset rstBranch.Open "Select * from Branch", DB, adOpenDynamic, adLockOptimistic 'Bind the form controls to database fields Set txtBrName.DataSource = rstBranch txtBrName.DataField = "BranchName" Set txtAssets.DataSource = rstBranch txtAssets.DataField = "Assets" 'Poplate branch city cboBrCity.AddItem "Mysore" cboBrCity.AddItem "Bangalore" cboBrCity.AddItem "Belgaum" cboBrCity.AddItem "Gulbarga" rstBranch.AddNew End Sub Private Sub txtAssets_Validate(Cancel As Boolean) If Not IsNumeric(txtAssets.Text) Then MsgBox "Please Enter Numbers in the Assets field", vbCritical, "Error in Data" txtAssets.SetFocus End If End Sub

Code for BranchExisting Form

Option Explicit Dim DB As Connection Dim rstBranch As Recordset Private Sub cmdBack_Click() Unload Me End Sub Private Sub Form_Load() 'Create connection object (for Oracle database) Set DB = New Connection DB.Open "DSN=Elective;UID=Prob5;PASSWORD=Prob5" 'Create recordset object Set rstBranch = New Recordset rstBranch.CursorLocation = adUseClient rstBranch.Open "Select * from Branch order by BranchName", DB, adOpenStatic,

adLockReadOnly Set DataGrid1.DataSource = rstBranch DataGrid1.Refresh End Sub

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Code for BranchDel Form

Option Explicit Dim DB As Connection Dim rstBranch As Recordset Private Sub cmdBack_Click() Unload Me End Sub Private Sub cmdDelete_Click() Dim ChoiceBranch As String Dim intChoice As Integer Dim strSQL As String If cboDelete.ListIndex = -1 Then MsgBox "You must select a Branch", vbExclamation cboDelete.SetFocus Exit Sub End If intChoice = MsgBox("Are sure you want to delete?", vbYesNo + vbCritical) If intChoice = vbYes Then ChoiceBranch = cboDelete.Text strSQL = "Delete from Branch where BranchName = " & "'" & ChoiceBranch & "'" DB.Execute strSQL MsgBox "Branch Successfully Deleted", vbInformation, "Delete Status" Unload Me End If End Sub Private Sub Form_Load() 'Create connection object (for Oracle database) Set DB = New Connection DB.Open "DSN=Elective;UID=Prob5;PASSWORD=Prob5" 'Create recordset object Set rstBranch = New Recordset rstBranch.CursorLocation = adUseClient rstBranch.Open "Select * from Branch order by BranchName", DB, adOpenStatic,

adLockReadOnly While Not rstBranch.EOF cboDelete.AddItem (rstBranch!BranchName) rstBranch.MoveNext Wend End Sub

This application has been tested with some sample data and found working at

all conditions.

11.6.6 Customer Database (Java2 and Oracle9i)

It is possible use Java2 as front-end tool for any DBMS. Let us show a simple

example by using Oracle9i as a back-end database. This tutorial should help you to

learn how to specify the DSN, ODBC driver and record set statements in a Java

program. Notice that most of the task is almost similar to VB6.0.

The steps to build this databse example are very simple. The first step is to

create a table named as ‘Customer’ in Oracle9i with columns <CustID, CustName,

Balance>. Next, specifiy CustID as primary key. The second step is to add few

records and commit. Ensure that the ODBSC DSN for Oracle exists with the name

‘Elective’.

This example uses JBuilder2005 to create the Java program. Create a java

project named as ‘customerdb’ and name the java program as ‘Customer.java’.

For the complete program and output, see the below program:

package customerdb; /** * JDBC - ODBC Demo (uses JBuilder 2005) * * Demo of how to connect to MS-Access Database from Java * it also shows how to retrieve the data from a table and display it * on the console * * Copyright: Copyright (c) 2005 * Company: BIT * @author S. Nandagopalan * @version 1.0 */ import java.sql.*; import sun.jdbc.odbc.*; class Customer { public Customer() { }

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public static void main(String[] args) { try { // Connect to the Database with DSN: 'Elective' new JdbcOdbcDriver(); /* For MS-Access String url = "jdbc:odbc:Elective"; // jdbc: <subprotocol> : <subname> String user = ""; String password = ""; Connection con = DriverManager.getConnection(url, user, password); Statement stmt = con.createStatement(); } */ // For Oracle 9i String url = "jdbc:odbc:Elective"; // jdbc: <subprotocol>: <subname> String user = "scott"; String password = "tiger"; Connection con = DriverManager.getConnection(url, user, password); Statement stmt = con.createStatement(); System.out.println("Succsfully connected to Customer Database"); // Insert a new row in the Customer Table // stmt.executeUpdate("INSERT into Customer VALUES //('1000','NEWC ','J C Road ',8967.25)"); // Retrieve the data from 'Customer' table System.out.println("The Customer Data:"); ResultSet rs = stmt.executeQuery("Select * from Customer"); double total = 0; String cid; String cname; double cbal; while (rs.next()) { cid = rs.getString(1); cname = rs.getString(2); cbal = rs.getDouble("Balance"); // column name is Balance System.out.println(cid + "\t" + cname + "\t" + cbal); total += cbal; } System.out.println("Total Balance = " + total); rs.close(); } catch (Exception e) { e.printStackTrace(); } } }

To use MS-Acces as back-end, simply remove the commented lines and

comment the Oracle9i connection statements. The program computes the sum of

the Balance column of all customers as shown in the next page.


Succsfully connected to Customer Database The Customer Data: 111 SNG 4500.0 222 Scott 9000.0 333 Allen 5600.0 Total Balance = 19100.0

Notice that cid, cname, and cbal are the host variables and assuming the table

Customer has only three records.

11.7 SUMMARY

This Chapter discussed several important points with regard to the database

application development

Simple tutorials were given to get the basic idea of developing VB6.0 based

applications. These tutorials used Oracle9i as the database where small tables

were created

Next, using the same front-end tool of VB6.0 it was shown how to make use of

tables created using MS-Access

Part-IV gave a very detailed and enterprise level database application

development called Company database. Readers can apply this example for

developing more sophisticated applications

Finally, a number of examples were shown to develop SQL queries.

11.8 EXERCISES

11.1 Design and develop a complete database application using Oracle9i and

VB6.0 for the following problems:

a) Hospital Management System (in-patient and out-patient)

b) Library Management (reference section, lending section, and journals)

c) Cricket Database Management

d) CD/DVD Library Management

e) On-Line Examination System

f) Inventory Control and Maanagement

g) Car Sales and Service Management

All the above database applications require images to be maintained. Suggest

the best and efficient way to store and retrieve images to and from the

database.

11.2 Identify some meaningful reports and implement them using VB's Data

Environment Report facility for the problems in 11.1.

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11.3 Develop suitable front-end for all the four additional problems dicussed in

Section 11.6. Also design some useful reports for the databases.

11.4 It is required to develop a database application for maintaining the student

database for a college. Design a complete application using Java2 and

Oracle9i.

Data Source Name (DSN), 457

Java2 and Oracle9i, 512

ODBC driver, 513

Report Generation, VB, 495

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