Visual Basic Applications (VBA)

Level I

By Ben Miu

What is Excel VBA?

• VBA is a MS Office based programming language modeled after Visual Basic 6.0

• Prior to VBA, automation in Excel was done with XLMMacros which lacked programming functionality

• Visual Basic evolved from BASIC, getting rid of the idea of structural programming

• Excel VBA is the end all of advanced Excel

Imagine …

• Many in AIMCo is doing manual tedious tasks of cutting and pasting spreadsheets

• Example: John is taking a file from a folder and creating a file folder then copying the file using Windows Explorer

• Example: Jim is manually drawing a line between two charts

• Example: Kim is manually cutting and pasting numbers from one spreadsheet to another

• Example: Simon is grabbing prices from a website on a daily basis and putting it into a spreadsheet

• What do all of these examples have in common?

Automation is the Answer

• VBA can copy files from a folder and put it into another folder. It can create files, delete directories

• VBA can draw lines between two charts and the code written can set business rules as to why you would do that

• VBA can cut and paste numbers without you even having to switch sheets

• VBA can access websites and grab information

Simply put, what can be imagined can be achieved with automation

Using the Macro Recorder

• Macro recorder is included in Excel. It is the most basic way of learning VBA and it’s where it all starts…

• Lab 1: Use the macro recorder to put the word “Ben” into Range A1. Examine the code, what do you see?

Advantages/Disadvantages of the Macro Recorder

Advantage:- Macro recorder has the ability to type code for you without you knowing ‘the code’- It can simplify your tasks if you are simply cutting and pasting the same cell everydayDisadvantage:- Lacks clear business logic abilities- Code is highly inefficient

The VBA Code Screen

• Alt-F11 opens up the code screen, or you can use the Developer Tab

• Macros may be disabled in Excel so you may need to tweak security settings, always save your files as .XLSM so you don’t lose your code

• Code is inserted into modules. Each time you use the recorder, a new module is created. Not necessarily the best approach

Code goes there

Recorder Code, before and after

After …

What happened?

• Macro recorder had to select each cell first and then used ambiguous activecell reference to change cell value

• The R1C1 doesn’t state anything about which cell you are changing and is not intuitive to people reading the code

• Code can be extremely long if you have to use the recorder for many entries

Why?

Workbooks(“Daily Risk.xlsm”).Sheets(“Sheet1”).Range(“A1”).Value = “Ben”

Workbooks Reference

Sheet Reference Range Reference

Value

Rewrite your lab using this syntax

The VBE Interface

Intermediates Window / Debug Window

Code inserted into a Subroutine

Modules hold code

Play and stop button

What is a variable?

• Variables store information into the computers memory for easy access

• Variables can contain text, numbers, dates, arrays, objects

• Example of creating a variableDim TotalAmount as Double

Choose a proper name for your variables

Types of Variables

• String – Text Only• Integer - -32768 to 32767 (Whole numbers only,

no decimals)• Long - -2,147,483,684 to 2,147,483,684(Whole

numbers only, no decimals)• Boolean – True or False• Double – Numbers with decimals• Any variables not declared with a dim statement

are assigned as Variant

Sample Code

Sub Test()

Dim TotalAmount as Double

TotalAmount = 100.00

Range(“A5”).Value = TotalAmount

End Sub ()

Declare variable

Assign variable

Procedure

If-Then-Else

• If-Then-Else is your most commonly used decision tree statement

• If Condition Then Code goes here

End If

If Condition ThenCode goes hereElseCode goes hereEnd If

If statements must always have a End If

Else statement executes code if condition is not met

Range vs. Cell

• Range(“A5”).Value = 100

• Cells(1,5).Value = 100

Both statements do the same thing. The Cells statement is useful if you know the row and column index number

String Concatenation

• You already know how to Dim a variable and assign a value to it

Dim SanaActivity as StringDim ActivityString as String

ActivityString = “Skiing”

SanaActivity = “Sana enjoys “ & Activitystring & “ very much”

Indenting your code and commenting your code

• Always important to indent your code• Use the ‘ to comment your code

Dim TotalAmount as DoubleTotalAmount = 100

If Range(“A5”).Value = 200 ThenRange(“A5”).Value = TotalAmountElseRange(“A5”).Value = “No”End If

‘Creates variablesDim TotalAmount as Double

‘Assigns variablesTotalAmount = 100

‘Assigns a proper value to the cellIf Range(“A5”).Value = 200 Then

Range(“A5”).Value = TotalAmountElse

Range(“A5”).Value = “No”End If

Bad Code

Good Code

Lab 2 – Writing your first programSub Test()

Dim CashAmount as Double

CashAmount = 100

If Range(“A1”).Value > 100 ThenMsgbox(“Less than 100”)

ElseIf Range(“A1”).Value < 100 ThenMsgbox(“Less than 100”)

ElseMsgbox(“Not a number”)

End If

End Sub

Try experimenting with theCashAmount variable by typing in:

CashAmount = (100 * 2) + 40

What happens if you type this in as the variable:

CashAmount = (100 * 2) + “JERRYYANG!”

For Next Loop• This type of loop is if you know how many iterations you need to go through• Counter variables are used to assist the For Next Loop in moving between

cells• What is a counter variable?• Counter variable is a variable which does nothing other than keep count

and holds a simple integer value• Example:

Dim I as Integer

I = 0

To increment a counter variable (not used in for next loops generally), you commonly use this notation I = I + 1

For Next Loop continued…

• Dim I as Integer I = 0

For I = 1 to 5Range(“A” & i).value = “Jerry”

Next

What does this code do?

Do While Loop

• This kind of loop is used if you are not sure how many iterations you need to go through

• It is used ‘while’ a condition is met. Once the condition is met, the loop kicks you out

• Commonly used is with a While/Wend loop moving through ranges/cells

Do While Loop Example

Dim I as Integeri = 1

Do While Range(“A” & I ).value = “Jerry”I = I + 1Msgbox(“Yang”)

Wend

Do Loop – Beware this one

• This loop is used if you do not want to put a condition into the loop but want to put a “Exit Do” into the Do Loop

• This loop is useful if you want a If-Then-Else statement to handle the exiting of the loop

• Beware this loop, as this one causes a infinite loop where there is no ending (unless you ESC out of the program)

Do Loop Example

Dim TotalAmount as DoubleTotalAmount = 100

DoMsgbox(“TotalAmount”)

Loop

Do you see a problem with this code?

Do Loop Proper Example

Dim TotalAmount as DoubleDim I as Integer

TotalAmount = 100I = 0

DoI = I + 1Msgbox(“OK”)If I = 5 Then Exit Do

Loop

New form of If statementDoesn’t require End If

Exit Do statement throws you out of the loop

Lab 3 – Lots of LoopsDim TotalAmount as DoubleDim I as IntegerDim SecretaryNameSecretaryName = “Sana Farrukh”TotalAmount = 100I = 0

Do While TotalAmount <> 0I = I + 1TotalAmount = TotalAmount - 1Range(“A” & i).Value = TotalAmount

Loop

For j = 100 to 1 Step -1Range(“B” & j).Value = SecretaryName

Next

I = 100

DoRange(“C” & i).Value = “Our Secretary name is “ & SecretaryNameI = I – 1If I = 1 Then Exit Do

Loop

Debugging and Error Trapping

• As you can see, if you mistype something, you get a Debug error message which will highlight the code that went bad

Ie.

Dim SecretaryName as StringSecretaryName = 33Error is Type Mismatch

Debugging and Error Trapping 2

• Putting stops in code. Click on the line to the left

Code Stops Here

Using Debug.Print

• Sometimes you want to find out the value of a variable as you run through your code

• You don’t necessarily want to stop your code as with the prior example of the RED dot

• So you use the Debug.Print to put the contents of a variable in the debug window

• Useful in loops where you want to see what the loop is doing to a variable or cell

Debug.Print statement insertedCan you think of where the value of “a.value”Will go to?

Perhaps here?

Do you see a problem with this if you are trying to deal with all AIMCo Employees?

Dim AIMCOEmployeeLeo as StringDim AIMCO EmployeeJagdeep as StringDim AIMCO EmployeeRyan as String

AIMCOEmployeeLeo = “Leo”AIMCOEmployeeJagdeep = “Jagdeep”AIMCOEmployeeRyan = “Ryan”

Perhaps an array helps

Dim AIMCOEmployee(250) as String

AIMCOEmployee(1) = “Leo”AIMCOEmployee(2) = “Jagdeep”AIMCOEmployee(3) = “Ryan”

Arrays

• An array is a variable which contain several values in itself and centralizes data contained

• To create an array you;Dim AIMCOEmployees(250) as String

AIMCOEmployees(1) = “Sana”AIMCOEmployees(2) = “Grant”AIMCOEmployees(3) = “Ryan”

And so on…

Lab 4• Put the following code into Excel VBA. What happens?

Dim RiskEmployees(3) as StringDim I as IntegerDim j as IntegerI = 0J = 0RiskEmployees(1) = “Ryan”RiskEmployees(2) = “Grant”RiskEmployees(3) = “John”

For I = 1 to 10Range(“A” & i).SelectFor j = 1 to 3

If Range(“A” & i).Value = RiskEmployees(j) Then Msgbox(“Great”)Next

Next

Nested loop. Wow!

Summary

• Macro Recorder• Creating Variables• If Then Else Loops• Do While Loops• Do Loops• Debugging and error trapping• Arrays

Thanks