FIX: Brackets Cause Recordset Update to Fail in SQL Server

• Microsoft Visual C++, 32-bit Editions, versions 2.0, 2.1, 2.2

SYMPTOMS

An MFC ODBC application in Visual C++ 2.x using a Microsoft SQL Server 6.0 data source may throw a CDBException when Update() is called to commit an AddNew() or Edit() for a recordset opened as snapshot. The following error is displayed in the output window of the debugger (DB tracing enabled):

Line 1: Incorrect syntax near '['.
State:37000,Native:170,Origin:[Microsoft][ODBC SQL Server Driver]
[SQL Server] 

CAUSE

The column name in an RFX function call in DoFieldExchange() needs to be enclosed in square brackets if the column name contains spaces or if it is a reserved word. These brackets need to be replaced with a driver-specific quotation mark before the SQL statement is sent for execution.

The quotation mark used by a particular driver can be retreived by calling SQLGetInfo() with the SQL_IDENTIFIER_QUOTE_CHAR argument. A Microsoft Access 2.0 data source uses a backward quotation mark (`). However, a double quotation mark (") and square brackets ([]) are also treated as quotation marks when used in this context. SQL Server 6.0 uses double quotation marks ("); square brackets ([]) will not work.

In the version of MFC that comes with Visual C++ version 2.x, CDatabase::ReplaceBrackets() is called while processing CRecordset::Open(). This function replaces the square brackets ([]) with the driver-specific quotation marks. However, this function is not called during AddNew/Update() or Edit/Update(). MFC builds an INSERT or UPDATE statement with column names and values when using snapshots. When the SQL statement generated with square brackets around field names is sent to SQL Server, the previously mentioned syntax error occurs because SQL Server does not recognize square brackets.

RESOLUTION

A simple workaround is to not use brackets around field names. If field names need to be enclosed, use the driver-specific quotation mark. For SQL Server, manually replace occurences of [field name] with "field name" inside the DoFieldExchange() function.

An alternative solution is to prevent the building of SQL statements with a list of column names for INSERT and UPDATE calls. This can be done by using dynasets instead of snapshots. However, to use dynasets with SQL Server 6.0, you must have a unique index. For further discussion of this issue, please see the following article in the Microsoft Knowledge Base:

Q136994 HOWTO: Use Dynasets with Microsoft SQL Server Version 6.0

STATUS

Microsoft has confirmed this to be a bug in the Microsoft products listed at the beginning of this article. This problem was corrected in Microsoft Visual C++ version 4.0.

Additional query words: 3.00 3.10 3.20

Keywords : kbprg kbDatabase kbMFC kbODBC kbVC
Version : 2.0 2.1 2.2
Platform : NT WINDOWS
Issue type : kbbug