DDL DML DCL and TCL

DDL DML DCL and TCL

In this post we will learn the basics of DDL, DML, DCL and TCL statements.

DDL(Data Definition Language )

statements are used to define the database structure or schema. Such as:

CREATE - to create objects in the database

ALTER - alters the structure of the database

DROP - delete objects from the database

TRUNCATE - remove all records from a table, including all spaces allocated for the records are removed

COMMENT - add comments to the data dictionary

RENAME - rename an object

 

DML(Data Manipulation Language)

statements are used for managing data within schema objects. Such as:

SELECT - retrieve data from the a database

INSERT - insert data into a table

UPDATE - updates existing data within a table

DELETE - deletes all records from a table, the space for the records remain

MERGE - UPSERT operation (insert or update)

CALL - call a PL/SQL or Java subprogram

EXPLAIN PLAN - explain access path to data

LOCK TABLE - control concurrency

DCL(Data Control Language)

       

GRANT - gives user's access privileges to database

REVOKE - withdraw access privileges given with the GRANT command

TCL(Transaction Control)

statements are used to manage the changes made by DML statements. It allows statements to be grouped together into logical transactions.

COMMIT - save work done

SAVEPOINT - identify a point in a transaction to which you can later roll back

ROLLBACK - restore database to original since the last COMMIT

SET TRANSACTION - Change transaction options like isolation level and what rollback segment to use

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Ref: http://www.orafaq.com/faq/what_are_the_difference_between_ddl_dml_and_dcl_commands