DOCUMENT:Q125767  12-JUN-2001  [odbc]
TITLE   :PRB: Query Too Complex Error After Execution of SQL Query
PRODUCT :Open Database Connectivity (ODBC)
PROD/VER:WINDOWS:2.0
OPER/SYS:
KEYWORDS:

======================================================================
2.00.2317

WINDOWS

kbprg kberrmsg

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

 - Microsoft Open Database Connectivity, version 2.0 
-------------------------------------------------------------------------------

SYMPTOMS
========

When you use the ODBC desktop drivers, the following message is displayed after
SQExecDirect or SQLPrepare fails with a SQL_ERROR return code:

   Query too complex

CAUSE
=====

There are two possible causes for this:

 - Application is running low on stack space.

 - The SQL query is hitting the defined SQL limits in the driver. For instance,
   the desktop database driver help files ODBCDRV.HLP and ODBCDRV32.HLP (16- and
   32-bit versions, respectively) list the SQL limitations:

   a. Maximum of 40 AND predicates in a WHERE clause.

   b. Maximum of 16 tables in a FROM clause.

   c. Maximum of 40 search conditions in a HAVING clause.

If a snapshot is created on a table with more than 40 columns, Microsoft
Foundation Classes (MFC) applications will get this error message on using the
CRecordSet::Update method. This is because the MFC database classes use the
Cursor Library for snapshots, and on a CRecordSet::Update, the Cursor Library
builds a WHERE clause listing all the columns in the table. This WHERE clause
has more than 40 AND predicates, therefore, an error is reported by the driver.

Note: An MFC ODBC application that references long binary data using the
RFX_LongBinary function may encounter this error when the recordset is opened.
This is because the cursor library precedes calls to SQLGetData with the
execution of a SELECT statement with a WHERE clause as described above.

The long binary column does not contribute toward exceeding the 40-column limit
because it is not referenced in the generated WHERE clause.

RESOLUTION
==========

To resolve the first cause above, you must set the stack size to 20K or more.

To resolve the second cause, where the error occurs on the CRecordSet::Update
method, you must:

 - Force MFC to use the native cursor functionality within the driver instead of
   using the Cursor Library. This is typically done by creating a dynaset
   instead of a snapshot, and be ensuring that the CDatabase object used by your
   CRecordset object does not load the cursor library. This is done by setting
   the fifth argument of CDatabase::Open to FALSE. (This also implies you will
   need to explicitly create and open a CDatabase object for your CRecordset
   object.)

   OR

 - Reduce the number of columns in the recordset.

Additional query words: 2.00.2317 Access dbase fox paradox 16bit 32bit MFC database classes Windows NT

======================================================================
Keywords          :  
Technology        : kbAudDeveloper kbODBCSearch kbODBC200
Version           : WINDOWS:2.0
Issue type        : kbprb

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

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 2001.