ACC: Tips for Debugging Visual Basic for Applications Code

      Function TestMe()
         Dim db As Database, rs As Recordset
         Dim empnum As Long
         Dim strsql As String
         Set db = CurrentDb()
         empnum = 5
         strsql = "select * from orders where [employeeid]=empnum"
         Debug.Print strsql
         Set rs = db.OpenRecordset(strsql)
      End Function

   Run this function in the Debug window by typing the following line
   and then pressing ENTER:

      ?TestMe()

   Note that the following result appears:

      select * from orders where [employeeid]=empnum;

   This Where condition shows [employeeid] = empnum, not [employeeid] = 5,
   as you assigned it. The cause is that the variable empnum needs to be
   exposed outside the SQL string. To fix this particular problem, change
   the Where condition to concatenate the empnum variable, as follows:

      Function TestMe()
         Dim db As Database, rs As Recordset
         Dim empnum As Long
         Dim strsql As String
         Set db = CurrentDb()
         empnum = 5
         strsql = "select * from orders where [employeeid]=" & empnum & ";"
         Debug.Print strsql
         Set rs = db.OpenRecordset(strsql)
      End Function


   When you run the corrected function in the Debug window, note that the
   following statement appears:

      select * from orders where [employeeid]=5;

Set a Watch Expression in Visual Basic for Applications Code

A watch expression is an expression that you monitor in the Debug window. You can observe the values of the watch expressions you select in the Watch pane. You can also perform an Instant Watch to see the value of an expression that hasn't been specified as a Watch expression. To add a Watch expression to the Watch pane, follow these steps:

1. Open the Debug window by pressing CTRL+G.

2. On the Debug menu (or the Tools menu in version 7.0), click Add Watch.

3. In the Expression box, type a variable, property, function call, or other valid expression.

4. In the Context box, set the scope of the expression you are watching by selecting the Procedure name and the Module name.

5. In the Watch Type box, click the option to determine how you want to evaluate the expression.

When the execution of your code is suspended, you can click Quick Watch on the Debug menu in Microsoft Access 97 to check the value of an expression that hasn't been defined as a Watch expression. You can also select an expression in your code and click the Quick Watch for it. (In Microsoft Access 7.0, you can use the Instant Watch command. You can also click the Instant Watch button on the Visual Basic toolbar to create a Watch expression from text you've selected in the Module window.)

Using the Calls Dialog Box to Trace Nested Procedures

The Calls dialog box displays a list of all active procedure calls. These calls are the procedures in an application that are started but not completed. You can use the Calls dialog box to trace the operation of an application as it runs a series of procedures. You can view the Calls from the Debug window by clicking the Build button.

The Calls dialog box lists all the active procedure calls in a series of nested procedure calls. It places the earliest active procedure call at the bottom of the list and adds subsequent procedure calls to the top.

You can use the Show button in the Calls dialog box to display the statement that calls the next procedure listed in the Calls dialog box. If you choose the current procedure in the Calls dialog box and then click Show, VBA displays the current statement at which execution was suspended.

Using the Locals Pane

The Locals pane in the Debug window has three columns: Expression, Value, and Type (or Context in version 7.0). The Expression column begins with the current module (for a standard module), or the current instance of a class (for a class module). The expression column is organized as a hierarchical tree of information starting from the current module to display all of the module-level variables in the current module. The Value column shows the values of the current module objects. You can change the value of a module- level variable in the Debug window in order to test the behavior of your module. The Type column shows the type of the current module-level object.

Inspecting a selected variable's value in the Locals pane can be very helpful in debugging your module, as can changing a variable's value in the Locals pane Value column to observe what effect it has on other parts of your module.

REFERENCES

For more information about the Debug window, search the Help Index for "Debug window."

For more information about debugging Visual Basic for Applications code, search the Help Index for "debugging code."

Keywords          : kbprg PgmErr kbfaq
Version           : 7.0 97
Platform          : WINDOWS
Hardware          : x86
Issue type        : kbinfo