PostgreSQL is an “Object Relational Database Management System
(ORDBMS)”. This database management system (DBMS) is similar to
a relational database but with an object-oriented database
model: objects, classes and inheritance are directly supported
in database schemas and in the query langauge. It supports a
large number of programming interfaces, including ODBC, Java
(JDBC), Tcl/Tk, PHP, Perl and Python. Let me explain some
advance feature of Postgresql: * Foreign keys * Transactional
integrity * Table Inheritance * Multiversion concurrency control
* Supports complex queries * Server side language: sql, java,
ruby, Paython, TCL, etc. Trigger is a specification that the
database should automatically execute a particular function
whenever a certain type of operation is performed. Triggers can
be defined to execute either before or after any INSERT, UPDATE,
or DELETE operation, either once per modified row, or once per
SQL statement. If a trigger event occurs, the trigger's function
is called at the appropriate