what is database languages and what is DML DDL and DCL in SQL

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                             DATABASE  LANGUAGES
(1) DATA DEFINITION LANGUAGE (DDL) --   the language used to define database is known as data definition language (DDL). The command used for defining database are known as DDL command. DDL includes all commands used for altering tables, dropping tables and defining constrains. 


(2) DATA MANIPULATION LANGUAGE (DML) -- the language that enable users to access or manipulate data is known as data manipulation language. The commands used for accessing and manipulating data are known as DML commands. DML includes commands for insertion, deletion, and updation besides retrieval. 

                                                    DMLs basically two types :

* procedural DMLs : it requires user to specify what data are needed and how to get those data. the codes generated by procedural DMLs is  efficient.


*Non-procedural DMLs : it requires user only to specify what data are needed.In non-procedural DMLs the user does not specify how to get those data . the code generated by non-procedural DMLs is less efficient as compared to procedural DMLs. 


(3) DATA CONTROL LANGUAGE (DCL) : The language used to control database is known as data control language (DCL). The commands used to control a database are known as DCL commands. DCL controls the database by administrating previlages & commiting (saving) of data. 


(4)TRANSACTION CONTROL LANGUAGE (TCL) : The process of performing operation over the database is known as transaction. when ever certain transaction is performed over database then it must be performed under the control. The language used to perform such operation is known as TCL. 
   

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