• Microsoft SQL Server 7.0
• SQL Server 2000 w/Service Packs 1, 2, 3, 3a
• SQL Server 2000 Desktop Engine (MSDE 2000)
• SQL Server 2000 Enterprise Edition (64-bit)
  
  Exceptions:
  1) dQuery does not support SQL Server Unicode field types
  2) Large SQL Server tables are opened read-only in dQuery

Oracle

• Oracle 8.0.5 and higher
• Oracle8i R1, R2, and R3 (8.1.5, 8.1.6, 8.1.7)
• Oracle9i R1 and R2 (9.0.1 and 9.2)
• Oracle 10g R1 (10.1)

Informix

• Informix Dynamic Server 9.2x, 9.3x, 9.4x

• DB2 Universal Database (UDB)
• DB2 Universal Database (UDB) v7.x, v8.1, and v8.2 for Linux, UNIX, and Windows via DRDA
• DB2 UDB v7.x and v8.1 for z/OS via DRDA

DB2 (AS400/iSeries Version)

• DB2 UDB V5R1, V5R2, and V5R3 for iSeries via DRDA
  
  Note: DB2 is built into the operating system of the AS/400, so the versions above actually refer to OS versions.

• Adaptive Server 11.5 and higher
• Adaptive Server Enterprise (ASE)
  12.0, 12.5, 12.5.1, 12.5.2, 12.5.3
  (dQuery also appears to support 15.x, but this version is not yet certified)

• The user may attempt to install third-party ODBC drivers for other databases. Some may work well, some may demonstrate exceptions. ODBC is used strictly at the user's risk. dBI does not certify third-party ODBC drivers.