Automating Tasks with Visual Basic

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.
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Automating Tasks with Visual BasicAutomatingTaskswithVisualBasicIntroductionqWhencan’t findareadymademacroactionthat doesthejobyouwant,youcanuseVisualBasic code.qExample: − Modifyawholebatchofrecordsatonce. − Performcomplexcalculations. − Interactwithotherprogramsoncomputer. − Write even more complicated validation routinesthatlockoutbaddata.UnderstandingVBATerminologyqSomebasicVBAterminology: − Statement: A word or combination of words thatconstitutesaninstructiontobeperformed bytheVBAengine. − Procedure: A collection of VBA statements thataregroupedtogethertoperformacertain task.Therearetwotypesofprocedures: Subroutines: perform a single task, no § return. Functions: performataskandthenreturna §UnderstandingVBATerminology− Module:Proceduresliveinmodules.Amodule consistsofoneormoreprocedures− Variable:isnothingmorethananameapplied to represent a data value. Variable is used to hold values such as customer names, dates, and numeric values manipulated by the VBA code.TheVisualBasicEditorqVisual Basic code is stored in database, but it need a different tool to view and edit it, called theVisualBasiceditor.qOpentheVisualBasiceditor: In the Access ribbon, choose Database § Tools➝Macro➝VisualBasicTheVisualBasicEditorqThe Visual Basic editor window is divided into threemainregions. − Projectwindow:showsallthemodulesinyour database. − Properties window: which shows settings for the currently selected item in the Project window. − Documentwindow:Editcoderegion.AddingaNewModuleqIntheVisualBasiceditor’smenu,chooseInsert ➝Module.AddingaNewModuleqWhenaddanewmodule,theVisualBasiceditor automatically opens a code window that shows thecontentsofthatmodule.qInitially,abrandnewmodulehasjustonelineof code: OptionCompareDatabase − ThislineisaninstructionthattellsVisualBasic howtohandleoperationsthatcomparepieces oftext.AddingaNewModuleqBefore write code you should add one more instructiontothetopofcodefile: OptionExplicitqThis instruction tells Visual Basic to use stricter error checking, which catches common typos whenusingvariables.SimplestPossibleCodeRoutineqEvery module are one or more subroutines. A subroutineisanamedunitofcodethatperforms adistincttask.qSubroutinesstartwiththeword Sub followedby the name of the subroutine and end with the statementEndSubqExample: SubMyCodeRoutine() MsgBoxWitnessthepowerofmycode. EndSubModuletypesqAccessstorescodeintwoplaces: − Classmodules:attachedtotheformorreport, itexecuteswhentheformorreportisopened, the class module does not appear in the modulessection. − Standard modules: Code can also be stored in modules section. Standard modules is accessibletoallobjectsinyourdatabase.RespondingtoaFormEventqOpenaforminDesignmode.qTurnoffControlwizardbutton.qAddanewbutton.qIn the Property Sheet, choose the Event tab, andthenselectthebutton’sOnClick eventqClicktheellipsis(…)intheOnClickEventboxqSelectCodeBuilderandclickOK