firebird 3.0.7 Relational database with many ANSI SQL standard features

Firebird is an SQL RDBMS with rich support for ANSI SQL (e.g., INSERT...RETURNING) including UDFs and PSQL stored procedures, cursors, and triggers. Transactions provide full ACID-compliant referential integrity.

The database requires very little manual maintenance once set up, making it ideal for small business or embedded use.

When installed as a traditional local or remote (network) database server, Firebird can grow to terabyte scale with proper tuning---although PostgreSQL may be a better choice for such very large environments.

Firebird can also be embedded into stand-alone applications that don't want or need a full client & server. Used in this manner, it offers richer SQL support than SQLite as well as the option to seamlessly migrate to a client/server database later.