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PostgreSQL Languages


1.DDL-Data Definition Language, which is used to create and modify the structure of database objects in database.
It's a auto commit. automatically saved when you create,alter,drop,truncate,comment,rename commands issued
ALTER – alters the structure of the existing database
CREATE – to create database and its objects like (table, index, views, store procedure, function and triggers)
DROP – delete objects from the database(Delete "data+metadata")
TRUNCATE – remove all records from a table, including all spaces allocated for the records are removed(Delete "data only performance is faster than delete")
COMMENT – add comments to the data dictionary
RENAME – rename an object

2.DML-Data Manipulation Language. which is used to store, modify, delete, insert and update data in database.
It's not a autocommit.it will save when u issue commit commands
INSERT – insert data into a table
UPDATE – updates existing data within a table
DELETE – Delete all records from a database table
MERGE – UPSERT operation (insert or update)
CALL – call a PL/SQL or Java subprogram
EXPLAIN PLAN – interpretation of the data access path
LOCK TABLE – concurrency Control

3.DRL-Data retrieval language. which is used to retrieve data from database
It's not a autocommit.it will save when u issue commit commands
SELECT - Retrieves data from a table

4.DCL-Data Control Language. which is used to create roles, permissions, and referential integrity as well it is used to control access to database by securing it.
It's not a autocommit.it will save when u issue commit commands
GRANT – Gives user’s access privileges to database
REVOKE – Withdraws user’s access privileges to database given with the GRANT command

5.TCL - Transaction Control Language. which dis used to manage different transactions occurring within a database.
It's not a autocommit.it will save when u issue commit commands
COMMIT – Saves work done in transactions
ROLLBACK – Restores database to original state since the last COMMIT command in transactions
SAVEPOINT – to rollback the transaction making points within groups
SET TRANSACTION – specify characteristics for the transaction


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