Friday, October 17, 2014

SQL Query Categories

Posted by Akarsh Nagariya at 2:01 PM Labels: MYSQL , ORACLE , SQL , TERADATA

SQL Query Categories:

DDL – It stands for Data Definition Language. These statement used to define the structure of database and schema.

CREATE – creates object in database
DROP – deletes object from database
ALTER – alters structure of database
TRUNCATE – Removes all records from a table
COMMENT – Add comment to data dictionary
RENAME – rename an object in database.

DML - Data Manipulation Language (DML) statements are used for data manipulation.

INSERT – inserts data into a table
SELECT – retrieve/fetch data from database
UPDATE – update existing data within a table
DELETE – deletes data from a table
UPSERT – Update on duplicate else insert data into a table

? Why Truncate is a DDL statement while delete is DML although both achieve same result??

DCL – Data Control Language (DCL) statements uses for control over data. It control access rights of users.

GRANT – gives access permission to database
REVOKE – withdraw access privilege given to user/users

· TCL – Transaction Control Language(TCL) statement controls atomicity of the statements. It controls transaction.

COMMIT –saves permanently into database.
ROLLBACK – Restore database to its previous stable state
SAVEPOINT – Identify a point to which transaction can be rolled back in case of any error/issue.
START TRANSACTION – Indicates starting point of transaction

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