Metabase is a DBMS-independent PHP API to access SQL databases. It supports MySQL, PostgreSQL, Oracle, Microsoft SQL server, Microsoft Access, ODBC, Interbase, Informix, MiniSQL, and SQLite. It supports nested transactions, blobs, and prepared queries. It can install database schemas defined in a DBMS independent XML format that describe tables, indexes, primary keys, and auto-increment sequences. It is also able to upgrade a database to a new schema without affecting the data that was stored since it was installed or upgraded for the last time. There is also schema reverse engineering support.