Valentina DB can be your SQL 92 compliant database, with or without object-relational extensions.
Valentina DB: The SQL Database
Valentina DB adheres to SQL standards but doesn't force you into making choices. The SQL extensions of Valentina DB to take advantage of Valentina DB special features are elegant, understandable and do not break standard SQL grammar. You can write SQL for Valentina object-relational features more simply and more effectively than existing SQL commands.