Qt

Qt has two drivers to access SQL Server databases: QTDS and QODBC. At the time of writing (January 2010) QTDS has a performance problem because rather than maintaining a connection, it instead re-connects for every query. So use QODBC.

There are however some problems with wide character support on Qt because Qt assumes sizeof(SQLWCHAR) == 2. On some DMs, though — including iODBC, the default on Ubuntu — sizeof(SQLWCHAR) == 4, which could lead to invalid character conversion.