1. Access VBA Programming for Beginners - Class 4 - by Patrick Lasu p_lasu@lycos.com

2. Class 4 - Overview Coding Concepts Coding Concepts –Reading Code –VB Operators/Characters: »Concatenation, Line Continuation, Comments –Stepping through Code IF Statements IF Statements IIF Statements IIF Statements Select Case Statements Select Case Statements

3. Coding Concepts Reading Code Reading Code –Reading code can be tricky »Statements to the left and right of an equal sign will not be equal until the code is executed (and then it can be “not equal” again). –Tip 1: Read (evaluate) from the right of the equal sign to figure it out –Tip 2: Do not worry about “past” statements

4. VBA Code intValue = 5 + 2 Next Line of Code Coding Concepts Behind the scenes 0 = 5 + 2 Next Line of Code Reading Code – Example 1

5. Behind the scenes 7 = 5 + 2 Next Line of Code VBA Code intValue = 5 + 2 Next Line of Code Coding Concepts Reading Code – Example 1

6. Behind the scenes 0 = 5 0 = 0 + 2 Next Line of Code VBA Code intValue = 5 intValue = intValue + 2 Next Line of Code Coding Concepts Reading Code – Example 2

7. Behind the scenes 5 = 5 5 = 5 + 2 Next Line of Code VBA Code intValue = 5 intValue = intValue + 2 Next Line of Code Coding Concepts Reading Code – Example 2

8. Behind the scenes 7 = 5 7 = 7 + 2 Next Line of Code VBA Code intValue = 5 intValue = intValue + 2 Next Line of Code Coding Concepts Reading Code – Example 2

9. Coding Concepts Concatenation character: Concatenation character: & (ampersand) & (ampersand) Used for putting expressions together Used for putting expressions togetherExample: strFirstName = “John” strLastName = “Doe” strFullName = strFirstName & “ “ & strLastName Avoid using ‘+’ to concatenate, it can produce unexpected results Avoid using ‘+’ to concatenate, it can produce unexpected results

10. Coding Concepts Line continuation character: Line continuation character: _ (underscore) _ (underscore)Example: Msgbox “This is important“, _ vbOKOnly, “My Message” String Example: strMsg= “This is a very important “ & _ “message from me!” Limit is 25 lines, or 24 line continuations Limit is 25 lines, or 24 line continuations

11. Coding Concepts Making comments Making comments –Use ‘ (apostrophe) to start a comment –Comments are not executed; used to document what the code is suppose to do »No need to write an essay Example: ‘Assign a value intValue=5 Rem Example: Rem Assign a value intValue=5

12. Coding Concepts Stepping through code Stepping through code –Use [F5] in the code window to execute the code –Use [F8] in the code window to execute the code one step at a time Works in a Standard Module, does not work in a Form Module. Works in a Standard Module, does not work in a Form Module.

13. IF Statement An IF statement evaluates a condition to find out if it is True or False, then executes the appropriate statement(s) An IF statement evaluates a condition to find out if it is True or False, then executes the appropriate statement(s) Type the word ‘If’ in the code window and press [F1] for help on the topic Type the word ‘If’ in the code window and press [F1] for help on the topic

14. IF Statement Syntax (Single Line): Syntax (Single Line): If condition Then [statements] [Else elsestatements] If Sales>100K Then Bonus=10% Else Bonus=1% Syntax (Multi-Line) Syntax (Multi-Line) If condition Then [statements] [Else [elsestatements]] End If Pseudo-code: If Sales>100K Then Bonus=10% Else Bonus=1% End If

15. IF Statement Syntax (If…Then…ElseIf…Then…Else) Syntax (If…Then…ElseIf…Then…Else) If condition Then [statements] [ElseIf condition-n Then [elseifstatements]... [Else [elsestatements]] End If If Sales>100K Then Bonus=10% ElseIf Sales>50K Then Bonus=5% Else Bonus=1% End If

16. IF Statement Nested IF Nested IF If condition Then [statements] [Else [elsestatements]] End If [Else [elsestatements]] End If Pseudo-Code: If Sales>100K Then If NewClients>5 Then Bonus=15% Else Bonus=10% End If Else Bonus=1% End If

17. IF Statement Operators for IF Statement condition Operators for IF Statement condition –Equal (=) –Not Equal (<>) –Less Than (<) –Less Than Or Equal To (<=) –Greater Than (>) –Greater Than Or Equal To (>=)

18. IF Statement Logical Operators Logical Operators –And –Or –Not –Xor –Eqv –Imp If Sales>100K And NewClients > 5 Then If Sales>100K Or NewClients > 10 Then If Not(Sales>100K) Then

19. Immediate IF Immediate If is similar to If statements Immediate If is similar to If statements –Syntax IIf(expr, truepart, falsepart) IIf(Sales>100K, Bonus=10%, 1%) –Can be nested IIf(expr, truepart, IIf(expr, truepart, falsepart)) IIf(Sales>100K, Bonus=10%, IIf(Sales>50K, Bonus=5%, Bonus=1%)) Type the word ‘IIf’ in the code window and press [F1] for help on the topic Type the word ‘IIf’ in the code window and press [F1] for help on the topic

20. Immediate IF The drawback is that it always evaluates both true and false part The drawback is that it always evaluates both true and false part –It is slower than IF statements –Can give unexpected results

21. Select Case Select Case is similar to If…Then…ElseIf statements. Select Case is similar to If…Then…ElseIf statements. The difference is that it evaluates an expression once and then compares it to different values The difference is that it evaluates an expression once and then compares it to different values –Makes it more efficient than multiple ElseIf statements Type the word ‘Select’ in the code window and press [F1] for help on the topic Type the word ‘Select’ in the code window and press [F1] for help on the topic

22. Select Case Syntax: Syntax: Select Case testexpression [Case expressionlist1] [statements] [Case expressionlist2] [statements] [Case Else] [statements] End Select Pseudo-Code: Select Case Sales Case >100K Bonus=10% Case >50K Bonus=5% Case Else Bonus=1% End Select