ADO Controls - Database Usage from Exploring MS Visual Basic 6.0 Book

Chapter 8Relational Databases

ActiveX Database Controls

8

Exploring Microsoft Visual Basic 6.0Copyright © 1999 Prentice-Hall, Inc.

By Carlotta Eaton

Exploring MS Visual Basic 6

Copyright 1999 Prentice-Hall, Inc. 2

Objectives...

1. Basic terminology such as tables and relationships

2. Use controls specialized for databases such as the data control, data-bound list box, data-bound combo box, and data-bound grid

3. Differences between FlexGrid control and data-bound grid control



Objectives

4. Implement a front-end application for an existing Access database

5. Use Visual Data Manager6. Create a new database application

with Application Wizard7. Create new forms with the Data

Form Wizard



Overview

Access is the relational database program included with Office Professional Edition

Minimize code using data-bound controls

Use standard ActiveX controls and the FlexGrid control



Relational Databases...

Relational databases - composed of tables and relationships

Table - consists of rows of records and columns of fields

Relationship - association between fields in two tables one-to-one one-to-many many-to-many



Relational Databases...

Primary key - field(s) that uniquely determines a record in a database

Foreign key - used to defined relationships between tables - a field in a table that also serves as a primary key in another table



Birthday Access DatabaseBirthdays Table

Occupations Table

Primary Key

Foreign Key



Database Controls...

Data control - use for each table we want to work with in the database

Data control Properties DatabaseName property - path and

filename of the existing database RecordSource property - select from

the list of tables in the database



Birthday Access Database

Data Control for the Occupations Table

Data Control for the Birthdays Table



ActiveX Database Controls...

Data-bound list control - displays a list box using a database field

Data-bound combo control - displays combo box using a database field

Data-bound grid control - displays a grid using a database field(s)



ActiveX Database Controls...Properties to set before utilizing

Row Source List Field Text

Properties used to update and manage the database Data Source Data Field Bound Column



ActiveX Database Controls

Properties must be set in order to work correctly1) Row Source2) List Field 3) Text Property4) Data Source5) Data Field6) Bound



Database Tools

Picture Label

Text boxCombo box

Check box

List box Data

Image OLE container

DBList DBGrid

DBCombo



More Properties

Data-bound Grid Control Data Source property

Intrinsic Data-Aware Control Properties Data Source property Data Field property



Managing and Displaying Records

Recordset - a record(s) selected from a table(s) in a databaseTable recordsets - limited to a single table, and

can modify recordsDynaset recordsets - can be used for multiple

tables, and can modify recordsSnapshot recordsets - can be used for multiple

tables, but cannot modify records



Navigating Records with Data Control Methods

Name.Recordset.Method

Where

Name is the name of the data control

Method is one of the following:

MoveFirst moves to the first record

MovePrevious moves to the previous record

MoveNext moves to the next record

MoveLast moves to the last record

Example:

datBirthdays.Recordset.MoveFirst



Finding Records with the Data Control


Where



FindFirst finds the first record

FindPrevious finds the previous record

FindNext finds the next record

FindLast finds the last record

Example:datBirthdays.Recordset.FindFirst “LastName = Dion”



Adding and Deleting Records with the Data Control


Where



AddNew adds a new record to the end of the database

Refresh redisplays the current record

Update modifies the fields in the current record

Delete deletes the current record from the database

Close closes the recordset, and frees the memory

allocated for storage

Example: datBirthdays.Recordset.AddNew



More Database Tools...

Different ways to access data ActiveX Data Objects (ADO) Remote Data Objects (RDO) Data Access Objects (DAO)



More Database ToolsLearning Edition Tools

ActiveX database controls Intrinsic data-aware controls

Professional Edition Tools Data View windows (new to VB 6.0) Data Environment Design Data Report feature

Enterprise Edition Tools Query Designer Database Designer



Add-Ins

Add-ins: tools that are programs that customize and extend the Visual Basic environment1) Add-ins: generic term2) Builders: helps view or set control properties3) Wizards: leads a user step-by-step through a

task4) Utilities: add-in that may be run outside Visual

Basic



Visual Data Manager

Add a Field Remove a Field



Summary ...

Access included with Microsoft Office Professional Edition

Relational databases composed of several tables and relationships

Relationships established between two tables using a foreign key



Summary ...

ActiveX database controls include Data-bound list box Data-bound combo box Data-bound grid control FlexGrid control

Data control must be used for each table we want to access



Summary ...

Navigate database using recordsets Table recordset Dynaset recordset Snapshot recordset

Define new databases using the Visual Data Manager add-in included in all 3 editions of Visual Basic



Summary

Data Form Wizard (new with VB 6.0) helps create database forms

Application Wizard creates general forms such as Splash and About forms for applications

ADO Controls - Database Usage from Exploring MS Visual Basic 6.0 Book

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