INF: SQLGetInfo Returned with SQL_PRESERVE_CURSORS

MORE INFORMATION

When the 2.50.0121 or later driver is running against a 6.0 or later SQL Server, applications can call:

SQLSetConnectOption(hdbc, SQL_PRESERVE_CURSORS, SQL_PC_ON);
				

to request that server side cursors be preserved across commits and rollbacks. After setting SQL_PC_ON, a call to SQLGetInfo to determine cursor commit behavior:

SQLGetInfo(hdbc1, SQL_CURSOR_COMMIT_BEHAVIOR,
       &rgbInfoValue, sizeof(rgbInfoValue), NULL);
				

still returns SQL_CB_CLOSE in rgbInfoValue, which indicates that cursors are closed on commits.

The driver reports SQL_CB_CLOSE because the SQL_PRESERVE_CURSORS option only applies to ODBC cursors which can be implemented using SQL Server 6.0 server cursors. Cursors which the driver cannot implement as server cursors must be closed before a commit or rollback can be issued on their connection handle, therefore not all cursors can be preserved across commits and rollbacks.

A discussion of the conditions under which SQL Server implements an ODBC Cursor as a server cursor can be found in the SQL Server ODBC help file, Drvssrvr.Hlp. It is also covered in the ODBC SQL Server Driver section of the SQL Server 6.0 "Books Online," where this is primarily discussed in the sections "Using ODBC Cursors" and "Advantages of Using Server Cursors." The SQL Server 6.5 "Books Online" discusses the same issues in Chapter 7 of "Programming ODBC for SQL Server."