After researching all the available databases which are free and source code is available, it was found that ONLY PostgreSQL is the MOST mature, most widely used and robust RDBMS SQL free database (object relational) in the world. PostgreSQL is very appealing as lot of work had already been done and it has ODBC, JDBC drivers using these it is possible to write applications independent of the databases. The applications written in PostgreSQL using ODBC, JDBC drivers are easily portable to other databases like Oracle, Sybase and Informix. And applications written for Oracle, Sybase and Informix using ODBC, JDBC drivers are easily portable to PostgreSQL database.