PRB: Running Genxtab with an Empty Table Causes Error

• Microsoft Visual FoxPro for Windows, version 3.0
• Microsoft FoxPro for Windows, versions 2.5, 2.5a, 2.5b, 2.6, 2.6a
• Microsoft FoxPro for MS-DOS, versions 2.5, 2.5a, 2.5b, 2.6, 2.6a

SYMPTOMS

When GENXTAB.PRG is run from an application, and the current table or cursor does not contain any records, GENXTAB.PRG issues one of the following error messages:

• Cannot prepare crosstab on empty database.

  -or-

• Variable '_WIN' not found.

CAUSE

Cross tabulation requires that a table or cursor (usually the result of a query) with only three fields be open in the selected work area.

RESOLUTION

Please see the workaround listed in the "More Information" section of this article.

STATUS

This behavior is by design.

MORE INFORMATION

Steps to Reproduce Behavior

1. Copy one of the following sections of code, depending on your version of FoxPro, to a PRG file. The SELECT, DO (_GENXTAB), and BROWSE NOMODIFY lines were created using the RQBE and copied to a PRG:

   Code for FoxPro 2.x -------------------

   IF !USED("customer")

         USE customer
   

   ENDIF

   STORE "C:\<FoxPro Directory>\GENXTAB.PRG" TO _GENXTAB

   SELECT Customer.cno, Customer.state, Customer.ytdpurch;

         FROM Customer;
         GROUP BY Customer.cno, Customer.state;
         ORDER BY Customer.cno, Customer.state;
         WHERE alltrim(upper(state))="JP" INTO CURSOR SYS(2015)
   

   DO (_GENXTAB) WITH 'Query' BROWSE NOMODIFY WAIT WINDOW "HELLO WORLD"

   The WHERE clause in the SELECT statement returns an empty cursor. Therefore, the BROWSE and WAIT WINDOW commands after the DO (_GENXTAB) WITH 'Query' will never get executed.

   Code for Visual FoxPro ----------------------

   IF !USED("customer")

            USE c:\vfp\samples\data\customer
      ENDIF
   
      SELECT Customer.cust_id, Customer.company, Customer.maxordamt;
       FROM customer;
       WHERE Customer.state = "WJ";
       GROUP BY Customer.cust_id, Customer.company;
       ORDER BY Customer.cust_id, Customer.company;
       INTO CURSOR SYS(2015)
       DO (_GENXTAB) WITH 'Query1'
      BROWSE NOMODIFY
      WAIT WINDOW "HELLO WORLD"
   
   

2. Create a new project, and add the program to the project.

3. Build an .EXE or .APP from the project.

4. Run the .EXE or .APP and notice that the BROWSE and WAIT WINDOW commands will not be executed.

Workaround

1. Replace the program listed above with the following:

   IF !USED("customer")

           USE customer
      ENDIF
   
      STORE "C:\<FoxPro Directory>\GENXTAB.PRG" TO _GENXTAB
   
      SELECT Customer.cno, Customer.state, Customer.ytdpurch;
         FROM Customer;
         GROUP BY Customer.cno, Customer.state;
         ORDER BY Customer.cno, Customer.state;
         WHERE alltrim(upper(state))="JP" INTO CURSOR SYS(2015)
   
      IF _TALLY !=0 &&if results are equal to 0 GENXTAB.PRG WILL NOT EXECUTE
         DO (_GENXTAB) WITH 'Query'
         BROWSE NOMODIFY
      ENDIF
   
      WAIT WINDOW "HELLO WORLD"
   
   

2. Create a new project, and add the program to the project.

3. Build an .EXE or .APP from the project.

4. Run the .EXE or .APP and notice that the WAIT WINDOW command is now executed.