data manipulation language comprises the SQL-data change statements, which modify stored data but not the schema of the database table. After the database schema has been specified and the database has been created, the data can be manipulated using a set of procedures which are expressed by DML. By Data Manipulation we mean, • Insertion of new information into the database • Retrieval of information stored in a database. • Deletion of information from the database.
• Modification of data stored in the database. The DML is basically of two types: Procedural DML – Requires a user to specify what data is needed and how to get it. Non-Procedural DML - Requires a user to specify what data is needed without specifying how to get it. SQL commands which comes under Data Manipulation Language are : Insert Inserts data into a table Update Updates the existing data within a table.
Delete Deletes all records from a table, but not the space occupied by them. 12th Computer Chapter - - . . DATA CONTROL LANGUAGE A Data Control Language (DCL) is a programming language used to control the access of data stored in a database.
It is used for controlling privileges in the database (Authorization). The privileges are required for performing all the database operations such as creating sequences, views of tables etc. SQL commands which come under Data Control Language are: Grant Grants permission to one or more users to perform specific tasks. Revoke Withdraws the access permission given by the GRANT statement.
. . TRANSACTIONAL CONTROL LANGUAGE Transactional control language (TCL) commands are used to manage transactions in the database. These are used to manage the changes made to the data in a table by DML statements.
SQL command which come under Transfer Control Language are: Commit Saves any transaction into the database permanently. Roll back Restores the database to last commit state. Save point Temporarily save a transaction so that you can rollback. .
. DATA QUERY LANGUAGE The Data Query Language consist of commands used to query or retrieve data from a database. One such SQL