SQL stands for structured query language. SQL is a kind of programming language specially designed for managing relational database management system (RDBMS). It is based upon relational algebra and tuple relational calculus.

The concept of relational data model for databases and its characteristics was coined by Edgar F. Codd. He had proposed few guidelines/ rules that must be followed by a database in order to be said as relational database. Codd’s 12 rules was the pioneer in laying the foundation of relational data model for databases.

Kindly refer for codd’s rule in detail at http://en.wikipedia.org/wiki/Codd%27s_12_rules.

SQL and its Uses:

SQL is standard medium to communicate with database and get relevant information queried. SQL queries/statements can be broadly classified into following four categories:

• DDL

• DML

• DCL

• TCL