008.module

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008.module

  1. 1. Automating Tasks with Visual Basic
  2. 2. 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.
  3. 3. 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
  4. 4. 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.
  5. 5. 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
  6. 6. 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.
  7. 7. Adding a New Module In the Visual Basic editor’s menu, choose Insert ➝ Module.
  8. 8. 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.
  9. 9. 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.
  10. 10. 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
  11. 11. 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 section. − Standard modules: Code can also be stored in modules section. Standard modules is accessible to all objects in your database.
  12. 12. Responding to a Form Event Open a form in Design mode. Turn off Control wizard button. Add a new button. In the Property Sheet, choose the Event tab, and then select the button’s On Click event Click the ellipsis (…) in the On Click Event box Select Code Builder and click OK

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