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Automating Tasks with Visual Basic Introduction • When can’t find a readymade macro action that does the job you want, you can use Visual Basic code • Example: – – – – Modify a whole batch of records at once Perform complex calculations Interact with other programs on computer Write even more complicated validation routines that lock out bad data Understanding VBA Terminology • Some basic VBA terminology: – Statement: A word or combination of words that constitutes an instruction to be performed by the VBA engine – Procedure: A collection of VBA statements that are grouped together to perform a certain task There are two types of procedures: • Subroutines: perform a single task, no return • Functions: perform a task and then return a value Understanding VBA Terminology – Module: Procedures live in modules A module consists of one or more procedures – Variable: is nothing more than a name applied to represent a data value Variable is used to hold values such as customer names, dates, and numeric values manipulated by the VBA code The Visual Basic Editor • Visual Basic code is stored in database, but it need a different tool to view and edit it, called the Visual Basic editor • Open the Visual Basic editor: • In the Access ribbon, choose Database Tools➝ Macro ➝ Visual Basic The Visual Basic Editor • The Visual Basic editor window is divided into three main regions – Project window: shows all the modules in your database – Properties window: which shows settings for the currently selected item in the Project window – Document window: Edit code region Adding a New Module • In the Visual Basic editor’s menu, choose Insert ➝ Module Adding a New Module • When add a new module, the Visual Basic editor automatically opens a code window that shows the contents of that module • Initially, a brand-new module has just one line of code: Option Compare Database – This line is an instruction that tells Visual Basic how to handle operations that compare pieces of text Adding a New Module • Before write code you should add one more instruction to the top of code file: Option Explicit • This instruction tells Visual Basic to use stricter error checking, which catches common typos when using variables Simplest Possible Code Routine • Every module are one or more subroutines A subroutine is a named unit of code that performs a distinct task • Subroutines start with the word Sub followed by the name of the subroutine and end with the statement End Sub • Example: Sub MyCodeRoutine() MsgBox "Witness the power of my code." End Sub ... Insert ➝ Module Adding a New Module • When add a new module, the Visual Basic editor automatically opens a code window that shows the contents of that module • Initially, a brand-new module has... Sub Module types • Access stores code in two places: – Class modules: attached to the form or report, it executes when the form or report is opened, the class module does not appear in the modules... Functions: perform a task and then return a value Understanding VBA Terminology – Module: Procedures live in modules A module consists of one or more procedures – Variable: is nothing more than a