SQL language has been an official standard since 1986. Technically, SQL is a "data sublanguage", which means it is used to the database. SQL is used in three ways:

-Interactive or stand-alone SQL is employed by users to directly extract impotent from or enter it into the database.

-Static SQL is fixed SQL code, written in advance rather than genera- ted at runtime, used in application. In embedded SQL, SQL code is incorporated into the source code of another language.

-Dynamic SQL is SQL code generated by an application at runtime. It is used instead of the static approach when the SQL code that would be needed cannot be determined at the time the application is written-it de- pends on chooses that the user makes.

The requirement of the three forms are different, and this is ref- lected in the language constructs used by each. Both static and dynamic SQL supplement stand-alone SQL with feature that are only applicable to their situation.