PRB: SQLCancel Instead of SQLFreeStmt Causes a Memory Leak

ID: Q159571

The information in this article applies to:

Microsoft SQL Server versions 6.0, 6.5
Microsoft Open Database Connectivity, version 2.5
Microsoft Visual Basic Enterprise Edition for Windows, version 4.0

SYMPTOMS

If an ODBC application uses SQLCancel instead of SQLFreeStmt to close an ODBC cursor after some data has been processed, the ODBC cursor library version 2.5 may generate a memory leak.

A Visual Basic 4.0 application may encounter this problem if the application uses the Requery method of an RDO Resultset. The ReQuery method internally invokes SQLCancel instead of SQLFreeStmt and SQL_CLOSE to close the statement handle, before binding the parameters and results.

CAUSE

An ODBC application should only call SQLCancel when dealing with asynchronous processing. ODBC applications should always use SQLFreeStmt and SQL_CLOSE rather than SQLCancel to close the statement handle.

For more information on how to use SQLCancel, please refer to Microsoft ODBC 2.0 Programmer's Reference and SDK Guide.

MORE INFORMATION

A Visual Basic application can call the Close and OpenRecordset methods instead of ReQuery. The Close method invokes SQLFreeStmt and SQL_CLOSE to close the statement handle.

Additional query words: 2.50 4.00

Keywords : SSrvProg
Version : WINDOWS:2.5,4.0; winnt:6.0,6.5
Platform : WINDOWS winnt
Issue type :