Friday 24 May 2013

SQL Commands, (DDL,DML,DCL,DQL,TCL)

SQL Commands:

The standard SQL commands to interact with relational databases are CREATE, SELECT, INSERT, UPDATE, DELETE, and DROP. These commands can be classified into groups based on their nature:

DDL - Data Definition Language:
Command
Description
CREATE
Creates a new table, a view of a table, or other object in database
ALTER
Modifies an existing database object, such as a table.
DROP
Deletes an entire table, a view of a table or other object in the database.
DML - Data Manipulation Language:
Command
Description
INSERT
Creates a record
UPDATE
Modifies records
DELETE
Deletes records
DCL - Data Control Language:
Command
Description
GRANT
Gives a privilege to user
REVOKE
Takes back privileges granted from user
DQL - Data Query Language:
Command
Description
SELECT
Retrieves certain records from one or more tables.


Transaction Control Language (TCL) –


These SQL commands are used for managing changes affecting the data. These commands are COMMIT, ROLLBACK, and SAVEPOINT

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