MS SQL Server, DB2 and Oracle have been the three databases supported since transition from Lombardi to IBM BPM, detailed requirements and specific version support can be obtained from this link http://www-01.ibm.com/support/docview.wss?uid=swg27023005
If you are writing generic toolkits or generic Process Applications for distributions and reuse it is a good practice to code conditionally for all three types of database syntaxes. In Lombardi days there used to be a service in PS toolkit which will provide you the type of database currently connected, but it should not be that difficult to dynamically run a query to obtain the database type.