PRB: ODBC SQL Server Driver and Access Violation on SQL Server (114630)

SYMPTOMS

When using the SQL Server ODBC driver with an ODBC enabled application to access SQL Server for Windows NT, an update on a table with a trigger which calls a stored procedure, which in turn contains an unmatched COMMIT TRAN or ROLLBACK TRAN statement, may cause an access violation to be encountered on SQL Server, causing SQL server to terminate.

In case of Access and Visual Basic, an attempt to update the SQL server table, will generate the following message,

ODBC - Update failed.

followed by:

[Microsoft][ODBC SQL Server Driver]Communication Link Failure.

For ODBC application writer, the following steps will encounter the behavior:

   // prepared execution to update the table
   SQLPrepare: update <tablename> set <col>= ? where <col>=?

   //Set parameters for the above prepared stmt
   SQLSetParam:

   //Begin transaction
   SQLSetConnectOption:
      fOption: SQL_AUTOCOMMIT
      vParam : FALSE or 0

   //Execute the previously prepared stmt
   SQLExecute:

This will return

SQL_ERROR, with szSqlState = "08S01", *pfNativeError = 0, *pcbErrorMsg = 61, szErrorMsg = [Microsoft][ODBC SQL Server Driver] Communication link failure.

WORKAROUND

This does not happen, if on SQL Server, the ROLLBACK TRAN or COMMIT TRAN statement itself is contained in the trigger instead of being in the stored procedure that is called by the trigger.

This happens only for prepared execution in ODBC. Thus, another workaround is to revoke stored procedure permissions from the users which will result in a non-prepared execution, and it will not cause access violation on the SQL Server.