creating more powerful applications: introduction to vba(wk9)

Exploring Office 2003 - Grauer and Barber 1

Creating More Powerful Applications: Introduction to

VBA(Wk9)


Objectives Describe the relationship of VBA to Microsoft

Office Create an event procedure Describe the VBA editor Distinguish between Procedure and Full

Module view Create a combo box to locate a record on a

form


Objectives (continued)

Describe MsgBox parameters

Facilitate data entry through keyboard shortcuts

Create an event procedure that substitutes an application-specific message for a standard Access error message

Describe several types of data validation


Case Study: Back to Natalie’s

Students will modify a database to include:

Modify Add Records procedure to move focus to the appropriate field on the form

Create a Find Record combo box and data entry shortcuts

Display a message reminding the user to backup the database upon close


Introduction to VBA

VBA is a subset of Visual Basic for all Microsoft Office applications

VBA is event driven

An event is any action recognized by Access

Procedures are sets of VBA statements that respond to specific events


A Better Student Form

A form used throughout this chapter that:

Improves on data validation

Facilitates data entry, including creating keyboard shortcuts

Employs error trapping

Enhances communication with the user by displaying dialog boxes


Procedures

Visual Basic code is developed in units called procedures

Event procedures: run automatically in response to events

General procedures: called explicitly from within another procedure


Modules All procedures are stored in modules; one or more

procedures per module

Every form in Access has its own 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


Module Window

Name of procedure(Form_Close)

MsgBox statement

End of procedure

Name of second procedure (Form_Current)


MsgBox function

MsgBox takes three arguments (parameters):

Prompt: Specifies the message text

Buttons: Type of command buttons and icon

Title: Text that appears in title bar of the message box


Hands-on Exercise 1

Title of Exercise: Create a Combo Box and Associated VBA Procedure

Objective: to create a combo box to locate a record; to create a VBA procedure to synchronize the combo box with the current record

Input file: Introduction to VBA Output file: Introduction to VBA (modified)


Create an Event ProcedureRight click on Form Selector box and choose properties

Select Event tab

Click On Current

Select Code Builder


On Current Event Procedure

Procedure header

Name of Combo Box from step 3

Complete Word willprovide completion options

Procedure View button


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


Hands-on Exercise 2

Title of Exercise: Facilitating Data Entry

Objective: Create keyboard shortcuts to facilitate data entry

Input file: Introduction to VBA (after Exercise 1) Output file: Introduction to VBA (modified)


KeyDown Event Procedure

Click drop-down arrowAnd select Form

Key words appear in blue

Click drop-down arrowAnd select KeyDown

Procedure View button


ShortCut Command Button

Select the commandButton PropertiesAll tab

Change Name toShortCutButton

Change Caption to&ShortCuts

Command button tool

Click and drag to create command button


Error Trapping Produce more user-friendly error message

Find error number using the Immediate window

Case statements test incoming variable value 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


Error Event Procedure

Error number

Case 1

Print MsgBox

Else statement


Hands-on Exercise 3

Title of Exercise: Error Trapping

Objective: to create an event procedure that substitutes application-specific messages for the standard Access error messages



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


MsgBox Functionvs.MsgBox 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


Hands-on Exercise 4

Title of Exercise: Data Validation

Objective: to use Field and Table properties to implement different types of data validation



Summary

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


Summary (continued)

All procedures are either public or private: Private: accessible only 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 Title bar message


End-of-chapter Exercises

Multiple Choice

Practice With Access Exercise 1 – MsgBox Examples Exercise 2 – Expanded Student Form Exercise 3 – Return to Soccer Exercise 4 – Enhancing a Report Exercise 5 – Acme Computers


End-of-chapter Exercises (continued)

On Your Own Expanding Soccer The VBA Primer Debugging Help for VBA


Questions?

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