Sql
- 1. Subject:DBMS (MCA, M.Sc., PGDCA ) Pratibha Rashmi Dr. Bhimrao Ambedkar University, Agra
- 2. SQL (Structured Query Language) is a computer language aimed to store, manipulate, and retrieve data stored in relational databases. IBM implemented the language, originally called Sequel, as part of the System R project in the early 1970s.. The first commercial relational database was released by Relational Software later becoming oracle.
- 3. DDL is abbreviation of Data Definition Language. It is used to create and modify the structure of database tables in database. CREATE – Creates tables in the database ALTER – Alters tables of the database DROP – Deletes tables of the database TRUNCATE – Deletes all records from a table and resets table identity to initial value.
- 4. DML is abbreviation of Data Manipulation Language. It is used to retrieve, store, modify, delete, insert and update data in database. SELECT – Retrieves data from a table INSERT - Inserts data into a table UPDATE – Updates existing data into a table DELETE – Deletes all records from a table
- 5. DCL is abbreviation of Data Control Language. It is used to create roles, permissions, and referential integrity as well it is used to control access to database by securing it. GRANT – Gives user's access privileges to database REVOKE – Withdraws user's access privileges to database given with the GRANT command
- 6. TCL is abbreviation of Transactional Control Language. It is used to manage different transactions occurring within a database. COMMIT – Saves work done in transactions ROLLBACK – Restores database to original state since the last COMMIT command in transactions SAVE TRANSACTION – Sets a savepoint within a transaction