FIX: Alter Table Add Primary Key Error Not Trappable

• Microsoft Visual FoxPro for Windows, versions 3.0, 3.0b

SYMPTOMS

When an existing ON ERROR routine is in effect, the following command causes an error, but that error is not trapped by the error routine.

   ALTER TABLE <tablename> ADD PRIMARY KEY <existing key tag>

The Help text topic states:

   Primary key already exists. (1883)

STATUS

Microsoft has confirmed this to be a problem in the Microsoft products listed at the beginning of this article. This problem has been corrected in Visual FoxPro 5.0 for Windows.

MORE INFORMATION

Steps to Reproduce Problem

1. Write a simple program, such as the following program, to illustrate this error and the error as it should be handled.

   ON ERROR WAIT WINDOW "Error" switch=.F. OPEN DATABASE C:\VFP\Samples\Data\testdata.dbc SELECT Customer DO WHILE .T.

        IF !switch
          ALTER TABLE Customer ADD PRIMARY KEY cust_id
        ELSE
          ALTER TABLE Customer ADD cust_id PRIMARY KEY
        ENDIF
        switch=!switch
   

   ENDDO

2. Name this program Altertst and save it.

3. In the Command window, enter the DO Altertst command.

4. Press ENTER at each pause

5. After successfully observing the two error modes, press ESC to cancel.

6. In the Visual FoxPro default directory, you will find an error log created in response to the ON ERROR handler named Altertst.err. This is a text file and may be read. It will have the offending line number and the report that the line has a syntax error.

7. Rerun the program. When the Microsoft Visual FoxPro message box appears, click the Help button to see the help text.