This document discusses programming in Visual Basic for Applications (VBA) in Microsoft Access 2013. It covers: 1. Using VBA to customize and automate an Access database through programming tools like macros and functions. 2. Creating subroutines and event procedures in standard modules to perform actions. Understanding event-driven programming where code execution is triggered by events. 3. Testing and debugging VBA code using tools like breakpoints, the immediate window, and watch window. Handling errors at different stages like syntax, compilation and run-time errors.

1. Succeeding in Business with Microsoft Access 2013
Enhancing User Interaction
Through Programming
Chapter 7

2. Succeeding in Business with Microsoft Access 2013
Chapter Introduction
• Visual basic for applications (VBA)
– Fully customize and automate a database
– Perform more complex validity checking
– Use functions and actions not available with
macros
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3. Succeeding in Business with Microsoft Access 2013
Tools Covered in This Chapter
• Assignment statement
• Breakpoints
• Code window
• DateDiff function
• DateSerial function
• Debug
• DoCmd statement
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4. Succeeding in Business with Microsoft Access 2013
Tools Covered in This Chapter (cont’d.)
• If statement
• Immediate window
• Variables
• Visual Basic editor
• Watch window
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5. Succeeding in Business with Microsoft Access 2013
Level 1 Objectives:
Writing Visual Basic for Applications Code
• Understand Visual Basic for Applications
programming
• Design, create, and test a subroutine in a
standard module
• Design, create, and test an event procedure
• Design, create, and test a function in a
standard module
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6. Succeeding in Business with Microsoft Access 2013
Understanding Visual Basic
for Applications
• Programming language for Microsoft Office
programs
– Including Access
• Common syntax and set of common features for
all Microsoft Office programs
• Features unique for each Microsoft Office
program
• Use programming language
– Write set of instructions to direct computer to
perform specific operations in specific order
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7. Succeeding in Business with Microsoft Access 2013
Understanding Visual Basic
for Applications (cont’d.)
• Coding
• Statement
• Event-driven language
• Object-oriented language
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8. Succeeding in Business with Microsoft Access 2013
Event-Driven Programming
• Event
– State, condition, or occurrence that Access recognizes
– Has associated event property
– Appears in property sheet for forms reports, and
controls
• Create group of statements using VBA code
– Set event property value to name of that group of
statements
– Event procedure
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9. Succeeding in Business with Microsoft Access 2013 9

10. Succeeding in Business with Microsoft Access 2013 10
Table 7.2: Common events for selected controls

11. Succeeding in Business with Microsoft Access 2013
Coding VBA
• Types of procedures
– Function procedures
• Performs operations
• Returns value
• Accepts input values
• Can be used in expressions
– Sub procedures
• Performs operations and accepts input values
• Does not return value
• Cannot be used in expressions
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12. Succeeding in Business with Microsoft Access 2013
Coding VBA (cont’d.)
• Module
– Group of related procedures
– Starts with Declarations section
– One or more procedures
• Basic types of modules
– Standard modules
• Database object stored in memory
• Use from anywhere in database
– Class modules
• Usually associated with particular form or report
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13. Succeeding in Business with Microsoft Access 2013
Coding VBA (cont’d.)
• Public procedure
– More than one object can use
• Local procedure or a private procedure
– Can only be used by the form or report for which
class module created
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14. Succeeding in Business with Microsoft Access 2013
Creating a Subroutine
in a Standard Module
• Replace macros with VBA procedures
– Better error handling and greater capabilities
– Some tasks cannot be performed with VBA
• AutoKeys
• AutoExec
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15. Succeeding in Business with Microsoft Access 2013
Creating a New Standard Module
• Click CREATE tab
– Click Module button in the Macros & Code group
• Begin new procedure in module
– Click Insert menu
– Click procedure
– Type name
– Select options
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16. Succeeding in Business with Microsoft Access 2013
Creating a New Standard Module (cont’d.)
• Visual Basic Editor (VBE)
– Create and modify VBA code
• Visual Basic window
– Program window that opens within VBE
• Code window
– Window to create modify and display specific VBA
procedures
– Can have as many code windows open as modules
in database
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17. Succeeding in Business with Microsoft Access 2013
Creating a New Standard Module (cont’d.)
• Sub statement
– Ends with End Sub statement
– Includes
• Scope of procedure
• Name of procedure
• Opening and closing parenthesis
• Option compare statement
– Designates technique Access uses to compare and
sort text data
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18. Succeeding in Business with Microsoft Access 2013
Creating a Subroutine
• Type statements in procedure between Sub
and End Sub statements
• DoCmd statement
– Executes action in procedure
– Access object
• Method
– Function or procedure that operates on specific
objects or controls
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19. Succeeding in Business with Microsoft Access 2013
Creating a Subroutine (cont’d.)
• Comment
– Include anywhere in VBA procedure
– Describe what procedure or statement does
• Make it easier for programmers to identify purpose of
statements
– Begin comment with
• Word Rem (for “remark”)
• Or single quotation mark (')
– Appear green in code window
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20. Succeeding in Business with Microsoft Access 2013
Creating a Subroutine (cont’d.)
• Line label
– Statement that serves as starting point for block of
statements in procedure
– Begins at start of line and ends with semicolon (;)
• Run procedure
– Click Run Sub/UserForm button
• Save module
– Click Save button
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21. Succeeding in Business with Microsoft Access 2013
Designing an Event Procedure
in a Form’s Class Module
• Associate procedure with form’s BeforeUpdate
event property
– Runs for the current record
– Triggered when moving to another record
• Add event procedure
– Open Property Sheet for form
– Switch to Event tab
– Click BeforeUpdate box list arrow
– Click [Event Procedure]
– Click Build button in BeforeUpdate box
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22. Succeeding in Business with Microsoft Access 2013
Using the If Statement in Decision Making
• Decision-making statement
– Executes group of statements based on outcome
of condition
– In simplest statement, Access executes a group of
statements if the condition is true
• Executes nothing if False
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23. Succeeding in Business with Microsoft Access 2013
Using the If Statement in Decision Making
(cont’d.)
• If statement
– Tests condition follows one of two paths
depending on outcome of condition
– General form
• If condition Then
– True-statement group
• [Else
– False-statement group]
• End If
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24. Succeeding in Business with Microsoft Access 2013
Using the If Statement in Decision Making
(cont’d.)
• Assignment statement
– Assigns value of expression to control or property
– Example
• EstSalary.ForeColor = vbGreen
• ForeColor property
• Color constants
– Predefined VBA names
– Have values that represent system color value
• IsNull function returns
– True value when field or control null
– False when not
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25. Succeeding in Business with Microsoft Access 2013
Testing an Event Procedure
• Switch to Form view
• Navigate through records
– Make sure results correct in different situations
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26. Succeeding in Business with Microsoft Access 2013
Using a Function in a Standard Module
• Similar calculation requests
– Create function to perform calculation
– Change the calculation in only one place to correct
an inaccuracy or enhance the calculation
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27. Succeeding in Business with Microsoft Access 2013
Using Functions in VBA
• Similar to way built-in functions used
– Access encounters a function name
– Executes the function
– Passes the argument values to the function
– The function performs its operations
– When finished, the calculated value replaces the
function in the expression
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28. Succeeding in Business with Microsoft Access 2013
Using Functions in VBA (cont’d.)
• VBA naming rules
– Must begin with letter
– Cannot exceed 255 characters
– Include letters numbers and underscore character
– Cannot use space, punctuation, or special characters
– Cannot be same as keywords or reserved words
– Each variable has data type
• A function begins with a Function statement and
ends with an End Function statement
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29. Succeeding in Business with Microsoft Access 2013 29

30. Succeeding in Business with Microsoft Access 2013
Using Variables
• Named location in computer memory
• Can contain value
• Use to store and retrieve data
• Reference a memory location using variable
name assigned to the location
• Holds only one value at a time
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31. Succeeding in Business with Microsoft Access 2013
Testing a Function in the Immediate Window
• When statement entered
– Editor checks statement to make sure syntax
correct
• Logic error
– Occurs when procedure produces incorrect results
• Immediate window
– Test VBA procedures without changing data in
database
– Enter different values to test procedure
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32. Succeeding in Business with Microsoft Access 2013
Testing a Function in the Immediate Window
(cont’d.)
• Immediate window
– Type keyword “print” or question mark (?)
– Followed by procedure name and argument
values to test in parentheses and separated by
commas
– Access executes the function and prints the value
returned by the function
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33. Succeeding in Business with Microsoft Access 2013
Modifying Functions
• A number of solutions can solve a single problem
– Some solutions are long and complicated
– Others are short and simple
• DateSerial function
– Returns a value for a specified year, month, and day
• Access stores
– A True comparison result as a zero value
– A False comparison result as a value of minus one (-1)
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34. Succeeding in Business with Microsoft Access 2013
Level 1 Summary
• VBA
– Programming language for Microsoft Office programs
• Create procedures in module
• Event-driven programming
– Program statement execution triggered by events
• If statement
– Used to make decisions
• Function
– Returns a value
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35. Succeeding in Business with Microsoft Access 2013
Level 2 Objectives:
Using Custom Functions and Verifying Data
• Design, create, and test a custom function in
an event procedure
• Verify data using event procedures
• Use the case control structure
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36. Succeeding in Business with Microsoft Access 2013
Enhancing an Event Procedure to Use a Custom
Function
• Add functionality to display a message or
perform a calculation
– Add a text box to display the message
– Add VBA statements to BeforeUpdate event
procedure so the focus changes to a new record
– Design decision-making logic in the VBA
procedure to perform the calculation
– Design additional decision-making logic to make
the text box control visible or not
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37. Succeeding in Business with Microsoft Access 2013
Using an ElseIf Statement
in an If Statement
• Date function
– Returns current computer system date
• ElseIf statement
– Equivalent to Else clause followed by If statement
• Choice of which If statement version used
– Matter of personal preference
• Arranging order of condition testing
– Order of condition testing critical
– Place conditions in order from least inclusive to most
inclusive
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38. Succeeding in Business with Microsoft Access 2013 38
Figure 7.14: Comparing an ElseIf clause with an Else…If clause

39. Succeeding in Business with Microsoft Access 2013
Using an ElseIf Statement
in an If Statement (cont’d.)
• Dim statement
– Declare variables and associated data types in
procedure
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40. Succeeding in Business with Microsoft Access 2013
Verifying Data with VBA
• Before Update event
– Occurs before changed data in control or record
updated in database
– Use to verify entered data
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41. Succeeding in Business with Microsoft Access 2013
Designing the Field Validation Procedure to
Verify Zip Codes
• Dim ZipFirstThree As Integer
– Declares the integer variable named ZipFirstThree
– Verifies that ZIP codes begin in the correct range
– Uses the built-in Val and Left functions
• Left function
– Returns string containing specified number of
characters from left side of specified string
• Val function
– Returns numbers contained in specified string as
numeric value
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42. Succeeding in Business with Microsoft Access 2013
Using the Case Control Structure
• Control structure
– Set of VBA statements work together as a unit
• Case control structure
– Evaluates expression
– Performs one of several alternative sets of
statements
– Based on resulting value (or condition) of
evaluated expression
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43. Succeeding in Business with Microsoft Access 2013
Using the Case Control Structure (cont’d.)
• Use Case Else statement as last Case
statement
– Include false-statement group
• SetFocus
– Moves focus to specified object or control
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44. Succeeding in Business with Microsoft Access 2013
Testing the Field Validation Procedure
to Verify ZIP Codes
• Switch to Form view to test validation
procedure
• Using event procedure for control or form
– BeforeUpdate event for each control on form
– Disadvantage
• All changes made to record canceled
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45. Succeeding in Business with Microsoft Access 2013
Designing the Field Validation Procedure to
Verify Phone Area Codes
• Must test first three digits of phone number
• Message can suggest potential error
– Must accept any phone area code entry
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46. Succeeding in Business with Microsoft Access 2013
Level 2 Summary
• ElseIf statement
• Case Control structure
• Verify data using VBA
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47. Succeeding in Business with Microsoft Access 2013
Level 3 Objectives:
Testing and Exploring VBA
• Troubleshoot VBA procedure errors
• Compile modules
• Develop sources for learning VBA
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48. Succeeding in Business with Microsoft Access 2013
Troubleshooting VBA Procedures
• Syntax error
– Occurs when VBA statement violates language
rules for statement such as
• Misspelling
• Incorrect sequence of keywords
• Missing parenthesis
– Detected immediately when statement completed
• Error message opens and explains error
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49. Succeeding in Business with Microsoft Access 2013 49

50. Succeeding in Business with Microsoft Access 2013
Troubleshooting VBA Procedures (cont’d.)
• Compilation error
– Occurs when procedures translated into form
computer cannot understand
• Compilation
– Process of translating modules from VBA to form
computer understands
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51. Succeeding in Business with Microsoft Access 2013
Troubleshooting VBA Procedures (cont’d.)
• Prevent compilation errors at run time
– Use Compile command on Debug menu
– Compile as last step before saving module
• Execution error or run-time error
– Occurs when procedure executes and stops
because it tries to perform operation that is
impossible to perform
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52. Succeeding in Business with Microsoft Access 2013
Using the Debugger to Correct Errors
• Breakpoint
– Run subroutine or function up until line on which
breakpoint set
– Procedure halts execution at breakpoint and
displays module screen
– Good way to isolate place at which procedure
stops producing anticipated result
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53. Succeeding in Business with Microsoft Access 2013
Using the Debugger to Correct Errors (cont’d.)
• Use mouse pointer to get more information
about procedure
– Pointing to variable name displays ScreenTip with
value contained in variable at point that
procedure halted
• Execute procedure one statement at a time
– Try and identify cause of error
– Click Debug on menu bar
• Click Step Into
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54. Succeeding in Business with Microsoft Access 2013
Using the Debugger to Correct Errors (cont’d.)
• Step Into
– Procedure executes next statement and stops
• Step Out
– Executes current subroutine or function and then
halts
• Reset button
– Stops debugger so you can fix problem
• Recompile and save
• When done, click Debug and Clear all Breakpoints
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55. Succeeding in Business with Microsoft Access 2013
Identifying Errors Using the Watch Window
• Watch window
– Shows current value of specified variable
• Add Watch dialog box
– Enter variable name to watch
• “<Out of context>” in Value column
– Appears for watch expression
– When Access not executing procedure that
contains watch expression
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56. Succeeding in Business with Microsoft Access 2013 56
Figure 7.28: Add Watch dialog box

57. Succeeding in Business with Microsoft Access 2013
Building Procedures Slowly
to Isolate Problems
• Prevent problems in procedures
– Build them slowly using small groups of
statements
– Prove them to be correct as you go
• Easier to correct small groups than long procedure
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58. Succeeding in Business with Microsoft Access 2013
Using Help to Learn More
About Programming and VBA
• Access Help contains useful information about
programming in Access and VBA
– F1 Help downloaded at installation
– Help button (? symbol) on the Ribbon
– Click in the Search box and type the topic you
would like to search
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59. Succeeding in Business with Microsoft Access 2013 59
Figure 7.32: Access Help on Visual Basic

60. Succeeding in Business with Microsoft Access 2013
Level 3 Summary
• Errors
– Syntax
– Compilation
– Execution or run-time
• Debugger
– Use to find and correct errors
• Help
– Learn more about VBA
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61. Succeeding in Business with Microsoft Access 2013
Chapter Summary
• Enhance a form using VBA procedures
– Subroutine
– Event procedure
– Code control structure adds to decision making
– Variables
• Custom functions
• Troubleshooting errors
– Breakpoints
• Access Help
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