Exploring Microsoft Access Chapter 8 Creating More Powerful Applications: Introduction to VBA By Robert T. Grauer Maryann Barber

Exploring Microsoft Office - Microsoft Access Chapter 8 2 Objectives (1 of 2)  Describe relationship of VBA to Microsoft Office  Describe components of the Module window  Describe two ways to create an event procedure  Explain how the Quick Info and Complete Word features simplify entry of VBA statements  Create a combo box to locate a record on a form

Exploring Microsoft Office - Microsoft Access Chapter 8 3 Objectives (2 of 2)  Describe MsgBox parameters  Create an event procedure to facilitate data entry through keyboard shortcuts  Create an event procedure that substitutes an application-specific message for the standard Access error messages  Describe several types of data validation

Exploring Microsoft Office - Microsoft Access Chapter 8 4 Overview  VBA is a programming language to build truly useful Access applications  VBA is event driven: Procedures respond to specific events  VBA can modify procedures that Access has already created  Provide an appreciation for what can be accomplished with VBA

Exploring Microsoft Office - Microsoft Access Chapter 8 5 Introduction to VBA  Data validation  Facilitate data entry, including creating keyboard shortcuts  Error trapping  Enhance communication with the user by using message boxes

Exploring Microsoft Office - Microsoft Access Chapter 8 6 Modules and Procedures  Visual Basic code is developed in units called procedures  Event procedures: run automatically in response to an event  General procedures: called explicitly from within another procedure

Exploring Microsoft Office - Microsoft Access Chapter 8 7 Modules  All procedures are stored in modules; one module contains one or more procedures  Every form in Access has its own module (Class module), which contains procedures for that form  Private procedure: accessible only from within the module in which it is contained  Public procedure: accessible from anywhere  Module window: where procedures in a module are displayed and edited

Exploring Microsoft Office - Microsoft Access Chapter 8 8 Module Window Name of procedure (Form_Close) MsgBox statement Name of next Procedure (Form_Current) End of procedure

Exploring Microsoft Office - Microsoft Access Chapter 8 9 MsgBox Statement  MsgBox takes three arguments (known as parameters)  Prompt: Specifies the message text  Buttons: Type of command buttons and icon  Title: Text that appears in title bar of the message box

Exploring Microsoft Office - Microsoft Access Chapter 8 10 Create an Event Procedure Select Event tab Click On Current Select Code Builder Right click on Form Selector box and choose Properties

Exploring Microsoft Office - Microsoft Access Chapter 8 11 On Current Event Procedure Procedure header Name of Combo Box from step 3 Complete Word will provide completion options

Exploring Microsoft Office - Microsoft Access Chapter 8 12 Facilitating Data Entry  Use the Default property to specify default values for certain fields  Use VBA to create keyboard shortcuts  A KeyDown event procedure can implement keyboard shortcuts

Exploring Microsoft Office - Microsoft Access Chapter 8 13 KeyDown Event Procedure Select Form in the Object list box Select KeyDown from the Procedure List box Key words Appear in blue

Exploring Microsoft Office - Microsoft Access Chapter 8 14 ShortCut Command Button Select the command button Properties All tab Change Name to ShortCutButton Change Caption to &ShortCuts Command Button tool

Exploring Microsoft Office - Microsoft Access Chapter 8 15 Error Trapping  Produce more user-friendly error message  Find the error number using the Immediate window  Use case statements to test the value of an incoming variable and produce the appropriate statement  Once error is detected, Call MsgBox statement to display your user-friendly error message  Else will execute if all Case statements fail

Exploring Microsoft Office - Microsoft Access Chapter 8 16 Error Event Procedure Case 1 Error numbers Case 2 Else statement

Exploring Microsoft Office - Microsoft Access Chapter 8 17 Data Validation  Invalid data corrupts validity of information  Data validation is therefore crucial  Use VBA to extend data validation capabilities within Access  Use a nested IF statement to remind users to leave no fields empty

Exploring Microsoft Office - Microsoft Access Chapter 8 18 MsgBox Function vs. Statement  MsgBox function: displays a prompt to the user, then returns a value - Requires parentheses around arguments  MsgBox statement: simply displays a message, does not use parentheses

Exploring Microsoft Office - Microsoft Access Chapter 8 19 Chapter 8 Summary (1 of 2)  VBA is a subset of Visual Basic  VBA is accessible by all Microsoft Office applications  All VBA procedures are stored in modules  Every form in Access has its own module that contains the event procedures for that form

Exploring Microsoft Office - Microsoft Access Chapter 8 20 Chapter 8 Summary (2 of 2)  All procedures are either public or private: Private—accessible only from within its module public—accessible from anywhere  Event procedures were created to illustrate how VBA is used to improve an application  MsgBox function has three arguments: message, intrinsic constant, and title bar message