PostgreSQL

PostgreSQL is probably the most advanced open source database in terms of programmability. PostgreSQL uses the language to perform SQL queries on the data. These are stored as a series of tables with foreign keys (n.d.t. foreign keys) that are used to connect related data. The programmability of PostgreSQL is its greatest strength and its primary advantage over its competitors: PostgreSQL makes it easier to build applications for the real world, using data taken from the database.

PostgreSQL