PRB: Running Genxtab with an Empty Table Causes Error

ID: Q126969

2.5x 2.60 2.60a 3.00 | 2.5x 2.60 2.60a

WINDOWS              | MS-DOS

The information in this article applies to:

• 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"

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"

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.

Keywords          : FxotherGeneral 
Version           : 2.5x 2.60 2.60a 3.00 | 2.5x 2.60
Platform          : MS-DOS WINDOWS