Databases with an ODBC driver and SQL support. Databases with only an ActiveX interface. Databases with only a DDE interface. If it's been designed to allow external applications to access it, just about any database will do. ODBC/ADO and SQL are the easiest. These are supported by NI's database toolkit and an open source LabVIEW tool. I've used SQL Server, Oracle, Access, MySQL, dBase.
