DOCUMENT:Q165066  04-FEB-2000  [foxpro]
TITLE   :FIX: Subquery Causes SUM to Return Incorrect Results
PRODUCT :Microsoft FoxPro
PROD/VER:WINDOWS:5.0
OPER/SYS:
KEYWORDS:kbvfp500aFIX kbvfp500bugkbbuglist kbfixlist

======================================================================
-------------------------------------------------------------------------------
The information in this article applies to:

 - Microsoft Visual FoxPro for Windows, version 5.0 
-------------------------------------------------------------------------------

SYMPTOMS
========

Including a subquery with a SQL-SELECT statement containing a SUM command causes
the SUM command to report incorrect amounts.

STATUS
======

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

MORE INFORMATION
================

The following code creates a table, populates it with data, and performs a
SELECT-SQL statement containing a subquery.

Steps to Reproduce Behavior
---------------------------

Create a program containing the following lines of code and execute it:

      *** Begin program code

      CLOSE ALL
      CREATE CURSOR Master ( nId I, cName C(10))
      INSERT INTO Master VALUES ( 1, "One")
      INSERT INTO Master VALUES ( 2, "Two")
      INSERT INTO Master VALUES ( 3, "Three")
      INSERT INTO Master VALUES ( 4, "Four")

      CREATE CURSOR Results ( nId I, dDate D)
      INSERT INTO Results VALUES ( 1, DATE())
      INSERT INTO Results VALUES ( 1, DATE())
      INSERT INTO Results VALUES ( 1, DATE())
      INSERT INTO Results VALUES ( 1, DATE())
      INSERT INTO Results VALUES ( 2, DATE() + 3)
      INSERT INTO Results VALUES ( 2, DATE() + 3)
      INSERT INTO Results VALUES ( 2, DATE() + 3)

      CREATE CURSOR Detail ( nId I, nAmount Y)
      INSERT INTO Detail VALUES ( 1, 100.00)
      INSERT INTO Detail VALUES ( 3, 300.00)

      * This will show correct sums
      WAIT WINDOW "Correct:" timeout 3
      SELECT Master.cName, ;
         SUM( NVL( Detail.nAmount, 0)) AS nSum ;
         FROM Master LEFT OUTER JOIN Detail ON Detail.nId = Master.nId ;
         GROUP BY 1

      * However, if I add an additional subquery, sum results are wrong.
      WAIT WINDOW "w/ Subquery - Wrong under VFP 5.0:" timeout 3
      SELECT Master.cName, ;
         SUM( NVL( Detail.nAmount, 0)) AS nSum ;
         FROM Master LEFT OUTER JOIN Detail ON Detail.nId = Master.nId ;
         WHERE Master.nId IN ( SELECT DISTINCT nId FROM Results ) ;
         GROUP BY 1

      CLOSE ALL
      *** End of program code

Executing the first query in Visual FoxPro 5.0 gives the following results:

   Cname       Nsum
   -----       -----
   Four        0.0000
   One         100.000
   Three       300.000
   Two         0.00000

The second query in Visual FoxPro 5.0, which contains the subquery, gives the
following incorrect results based on the same data:

   Cname       Nsum
   -----       -----
   One         0
   Two         0

In Visual FoxPro 5.0a, the results of the first query remain the same. However,
the second query correctly returns to following values:

   Cname       Nsum
   -----       -----
   One         100.0000
   Two         0.0000

Additional query words: 5.0

======================================================================
Keywords          : kbvfp500aFIX kbvfp500bug kbbuglist kbfixlist
Technology        : kbVFPsearch kbAudDeveloper kbVFP500
Version           : WINDOWS:5.0
Issue type        : kbbug
Solution Type     : kbfix

=============================================================================

THE INFORMATION PROVIDED IN THE MICROSOFT KNOWLEDGE BASE IS
PROVIDED "AS IS" WITHOUT WARRANTY OF ANY KIND.  MICROSOFT DISCLAIMS
ALL WARRANTIES, EITHER EXPRESS OR IMPLIED, INCLUDING THE WARRANTIES
OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE.  IN NO
EVENT SHALL MICROSOFT CORPORATION OR ITS SUPPLIERS BE LIABLE FOR
ANY DAMAGES WHATSOEVER INCLUDING DIRECT, INDIRECT, INCIDENTAL,
CONSEQUENTIAL, LOSS OF BUSINESS PROFITS OR SPECIAL DAMAGES, EVEN IF
MICROSOFT CORPORATION OR ITS SUPPLIERS HAVE BEEN ADVISED OF THE
POSSIBILITY OF SUCH DAMAGES.  SOME STATES DO NOT ALLOW THE EXCLUSION
OR LIMITATION OF LIABILITY FOR CONSEQUENTIAL OR INCIDENTAL DAMAGES
SO THE FOREGOING LIMITATION MAY NOT APPLY.

Copyright Microsoft Corporation 2000.