What is DDL, DML, DCL and TCL?

DDL

A data definition language or data description language (DDL) is syntax similar to a computer programming language for defining data structures, especially database schemas.

CREATE	To create database and its objects like (table, index, views, store procedure, function and triggers)
ALTER	Alters the structure of the existing database and its objects
DROP	Delete objects from the database
TRUNCATE	Remove all records from a table, including all spaces allocated for the records
RENAME	Renames an object
COMMENT	Add comments to the data dictionary

DML

DML stands for Data Manipulation Language to retrieve and manipulate data in a relational database, and includes most common SQL statements such SELECT, INSERT, UPDATE, DELETE etc, and it is used to store, modify, retrieve, delete and update data in database.

Data manipulation language comprises the SQL data change statements, which modify stored data but not the schema.

Data manipulation languages have their functional capability organized by the initial word in a statement, which is almost always a verb. In the case of SQL, these verbs are:

SELECT	Retrieve data from the database.
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	Explain access path to data
LOCK TABLE	Control concurrency

DCL

DCL stands for Data Control Language used to control access to data stored in a database.

GRANT	Providing  user with set of roles to access database
REVOKE	Withdraw user’s access privileges already given

TCL

TCL is short name of Transaction Control Language which deals with transaction within a database. TCL statements are used to manage the changes made by DML statements. It allows statements to be grouped together into logical transactions.

COMMIT	Saves the work done
ROLLBACK	Restore database to original since the last COMMIT
SAVEPOINT	Identify a point in a transaction to which you can later roll back
SET TRANSACTION	Change transaction options like isolation level and what rollback segment to use