PostgreSQL is an open source object-relational-database system that exists more than 15 years. PostgreSQL can be run on all major operating systems, including Linux, UNIX (AIX, BSD, HP-UX, SGI IRIX, Mac OS X, Solaris, Tru64), and Windows. PostgreSQL has full support for foreign keys, joins, views, triggers, and stored procedures (in multiple languages). It includes most SQL:2008 data types, including INTEGER, NUMERIC, BOOLEAN, CHAR, VARCHAR, DATE, INTERVAL, and TIMESTAMP. PostgreSQL also supports storage of binary large objects, including pictures, sounds, or video. PostgreSQL has native programming interfaces for C/C++, Java, .Net, Perl, Python, Ruby, Tcl, ODBC, among others, and exceptional documentation.
Frontware proposes PostgreSQL as an alternative rather than MS SQL Server because it's powerful, easy to install and free. The couple Ubuntu 11.04 x64 Server + PostgreSQL 9.0 is the database solution Frontware proposes if the customer wants to avoid Microsoft licenses fee for Windows Server + MS SQL 2008. Any .Net application can access the PostgreSQL database without any problem or any client license. Of course any PHP application or ASP .Net can access it too. PostgreSQL is very secure, offering a SSL connection between client and server. We prefer PostgreSQL to Mysql because PostgreSQL is real open source, very capable on high load work and enforcing data integrity.
PostgreSQL is the Odoo database, it's safe, fast and complete open source solution for ERP. See more details here.