microsoft access 2013 ®® tutorial 11 using and writing visual basic for applications code

Microsoft Access 2013

® ®

Tutorial 11Using and Writing Visual Basic for

Applications Code

XPXPXPObjectives• Session 11.1– Learn about user-defined functions, Sub

procedures, and modules – Review and modify an existing Sub procedure in an

event procedure– Create a function in a standard module– Test a procedure in the Immediate window

New Perspectives on Microsoft Access 2013 2

XPXPXPObjectives• Session 11.2– Create event procedures – Compile and test functions, Sub procedures, and

event procedures– Create a field validation procedure


XPXPXPIntroduction to Visual Basic for Applications• Case - Chatham Community Health Services

Creating VBA Code for the Health Database

• User would like to modify the frmVisit, frmPatient, and frmVisitsAndInvoices forms to make data entry easier and to highlight important information on them

• To make these modifications, you will write Visual Basic for Applications code to perform the necessary operations


XPXPXPIntroduction to Visual Basic for Applications (Cont.)


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Introduction to Visual Basic for Applications (Cont.)

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• Visual Basic for Applications (VBA)– The programming language provided with Access

and other Office programs– VBA has a common syntax and a set of common

features for all Microsoft Office programs, but it also has features that are unique for each Microsoft Office program due to each program’s distinct structure and components

• Coding – The process of writing instructions in a

programming language

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• Statement– The VBA instructions to respond to an event that

occurs with an object or a form control in a database• An event could be a click on a button, or activating a

textbox control.

• Event-driven language– Events in the database trigger a set of instructions

• Object-oriented language– Each set of instructions operates on objects in the

database

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• Events– A state, condition, or action that Access recognizes

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• Procedures– A group of statements to perform a set of

operations• User-Defined function– Performs operations, returns a value, accepts input

values, and can be used in expressions• Sub procedure– Executes instructions and accepts input values, but

does not return a value and cannot be used in expressions

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• Modules– A group of related procedures together in an

object• Declarations section– Contains statements that apply to all procedures in

the module• Standard module– A database object that is stored in memory with

other database objects (queries, forms, and so on) when you open the database

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• Public procedure– A procedure that more than one object can use

• Class module– Usually associated with a particular form or report– When you create the first event procedure for a form or

report, Access automatically creates an associated form or report class module

– When you add additional event procedures to the form or report, Access adds them to the class module for that form or report

– Each event procedure in a class module is a local procedure, or a private procedure

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Using an Existing Procedure

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Using an Existing Procedure (Cont.)

• Displaying an Event Procedure– The VBA procedure that controls the display of the

message and its color for each record is in the class module for the form

– Access processes the statements in the procedure when you open the form and also when the focus leaves one record and moves to another

– The event called the Current event occurs when the focus shifts to the next record loaded in a form, making it the current record.

– The OnCurrent property contains a reference to a macro, VBA code, or some other expression that runs when the Current event occurs

XPXPXPUsing an Existing Procedure (Cont.)




• Visual Basic Editor (VBE)– The program you use to create and modify VBA code

• Visual Basic Window– The program window that opens when you use VBE

• Scope– Indicates where the procedure is available– If the scope is public, the procedure is available in all

objects in the database– If the scope is private, the procedure is available only in the

object in which it is created– Event procedures are private, by default



• Control Structure– The set of VBA statements that work together as a unit

• Conditional Control Structure– The evaluates an expression—the value of the Reason field

and then performs one of several alternative actions based on the resulting value (or condition) of the evaluated expression



• Modifying an Event Procedure

XPXPXPCreating Functions in a Standard Module


• String– The or more characters that could include alphabetic

characters, numbers, spaces, and punctuation

• AfterUpdate Event– Triggered when a user enters or changes a field value in a

control or in a form and then changes the focus

XPXPXPCreating Functions in a Standard Module (Cont.)


• Creating a Function– Each function begins with a Function statement

and ends with an End Function statement– You’ll start the function with the function name

and followed by a parameter, which is the value passed to the function -- called an argument

XPXPXPTesting a Procedure in the Immediate Window


• Logic Error– Occurs when a procedure produces incorrect results

• Immediate window– Allows you to test VBA procedures without changing any

data in the database

XPXPXPCreating an Event Procedure


XPXPXPCreating an Event Procedure (Cont.)




• Designing an Event Procedure– If Statement• Executes one of two groups of statements based on a

condition, similar to common English usage• True-statement group - What happens if the condition is true

• False-statement group - What happens if the condition is false



• Adding an Event Procedure



• Compiling Modules



• Testing an Event Procedure

XPXPXPAdding a Second Procedure to a Class Module


• Designing the Field Validation Procedure

XPXPXPAdding a Second Procedure to a Class Module (Cont.)


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• Variable– A named location in computer memory that can contain a

value

• Dim statement– Used to declare variables and their associated data types in

a procedure

Adding a Second Procedure to a Class Module (Cont.)


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• Adding a Second Event Procedure

Adding a Second Procedure to a Class Module (Cont.)


XPXPXPAdding a Second Procedure to a Class Module (Cont.)


XPXPXPChanging the Case of a Field Value


• The StrConv function converts the letters in a string to all uppercase letters or to all lowercase letters, or converts the first letter of every word in the string to uppercaseletters and all other letters to lowercase letters,

[Address] = StrConv([Address], vbProperCase)• The vbProperCase constant, is a VBA constant that specifies

the conversion of the first letter in every word in a string to uppercase letters and the conversion of all other letters to lowercase letters

• Other VBA constants you can use are the vbUpperCase constant, which specifies the conversion of the string to all uppercase letters, and the vbLowerCase constant, which specifies the conversion of the string to all lowercase letters

XPXPXPChanging the Case of a Field Value (Cont.)


XPXPXPHiding a Control and Changing a Control’s Color


XPXPXPHiding a Control and Changing a Control’s Color (Cont.)


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