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MS Access: Naming Variables (Programming Standards)

We try to prefix all variables with a letter indicating the scope of the variable. This makes it easier to figure out where the variable has been declared.

Here is a quick summary of the naming conventions that we use:

Scope	Example	Explanation
Global	GClient_ID	All global variables should be prefixed with "G".
Local	LClient_ID	All local variables should be prefixed with "L".
Parameter	pClient_ID	All parameters should be prefixed with "p".

Global Variables

What is a Global variable?

A Global variable is one that can be accessed from anywhere in your program. We try to prefix all Global variables with "G".

For example, you could create a global variable called GClient_ID with the following command:

Global GClient_ID As Integer

Global variables are generally declared at the top (ie: Declarations section) of a module.

Local Variables

What is a Local variable?

A Local variable is one that exists only within the current function or subroutine. We try to prefix all Local variables with "L".

For example, you could create a local variable called LTotalDays with the following command:

Dim LTotalDays As Integer

Local variables are generally declared at the top (ie: Declarations section) of a function or subroutine.

Below is an example of a function:

Function Example1() As Integer

   Dim LTotalDays As Integer
   Dim LSaturdays As Integer
   Dim LSundays As Integer

   LTotalDays = DateDiff("d", StartDate, EndDate)
   LSaturdays = DateDiff("ww", StartDate, EndDate, 7)
   LSundays = DateDiff("ww", StartDate, EndDate, 1)

   'Elapsed days excluding Saturdays and Sundays
   Example1 = LTotalDays - LSaturdays - LSundays

End Function

In this example, we've created three local variables - LTotalDays, LSaturdays, and LSundays.

Parameters

What is a Parameter?

A Parameter is a variable that is used to pass information to or from a function or subroutine. We try to prefix all parameters with "p".

For example, we could create parameters in a function as follows:

Function Example2(pStartDate As Date, pEndDate As Date) As Integer

   Dim LTotalDays As Integer
   Dim LSaturdays As Integer
   Dim LSundays As Integer

   LTotalDays = DateDiff("d", pStartDate, pEndDate)
   LSaturdays = DateDiff("ww", pStartDate, pEndDate, 7)
   LSundays = DateDiff("ww", pStartDate, pEndDate, 1)

   'Elapsed days excluding Saturdays and Sundays
   Example2 = LTotalDays - LSaturdays - LSundays

End Function

In this example, we've created a function with two parameters - pStartDate and pEndDate.

You could also create parameters in a subroutine as follows:

Sub Example3(pStartDate As Date, pEndDate As Date)

   Dim LTotalDays As Integer

   LTotalDays = DateDiff("d", pStartDate, pEndDate)

   'Elapsed days
   MsgBox "There are " & LTotalDays & " elapsed days."

End Sub

In this example, we've created a subroutine with two parameters - pStartDate and pEndDate.