Microsoft Access 2010 : Learning the Basics of Creating and Running a Macro (part 2) - Submacros, Program Flow

Submacros

Submacros are like subroutines in a programming module; they allow you to place more than one routine in a macro. This means you can create many macro routines without having to create several separate macros. You should include submacros that perform related functions within one particular macro. For example, you might build a macro that contains all the routines required for form handling and another that has all the routines needed for report handling.

Only two steps are needed to add submacros to a macro:

1.

Click and drag a submacro from the Action Catalog onto the macro. A submacro appears as in Figure 7. Figure 7. The submacro allows you to create subroutines within a macro.

2.

Add macro actions to each submacro. Figure 8 shows a macro with three submacros: OpenCustomers, OpenOrders, and CloseForm. The OpenCustomers submacro opens the Customer List form, showing all customers. The OpenOrders submacro opens the OrderList form displaying only orders placed in March and April of 2006, and the CloseForm submacro displays a message to the user and then closes the active window.

Figure 8. A macro with three submacros.

Program Flow

At times, you want a macro action to execute only when a certain condition is true. Fortunately, Access allows you to specify the conditions under which a macro action executes:

Figure 9. You can designate the condition under which a macro action executes by selecting If from the Program Flow node of the Action Catalog.

The macro pictured in Figure 10 evaluates information entered on a form. The macro evaluates the date entered in the txtBirthDate text box on the frmPersonalInfo form. Here’s the expression entered in the first condition:

DateDiff("yyyy",[Forms]![frmPersonalInfo]![txtBirthDate],Date()) Between 25 And 49

					  

Figure 10. An example of a macro containing conditions.

This expression uses the DateDiff function to determine the difference between the date entered in the txtBirthDate text box and the current date. If the difference between the two dates is between 25 and 49 years, a message box is displayed indicating that the person is over a quarter century old.

If the first condition isn’t satisfied, the macro continues evaluating each condition. The CheckBirthDate subroutine displays an age-specific message for each person 25 years of age and older. If the person is younger than 25, none of the conditions are met, and no message is displayed.

The CheckGender macro works a little bit differently (see Figure 11). It evaluates the value of the fraGender option group. One of the first two lines of the subroutine execute, depending on whether the first or second option button is selected. The third line of the subroutine executes regardless of the Option Group value because it is after the End If.

Figure 11. An example of a macro containing conditions.