Basic Introduction of SQL & MySql

SQL is declarative language-

 * Main component of SQL syntax:

    1: DDL(Data defination Language);

    2: DML(Data Manipulation language);

    3: DCL(Data Control Language);

    4: TCL(Transaction control language)


#DDL : A set of statement that allow the user to define or modify data structures and  objects, such as tables.It  contains - CREATE , ALTER , DROP , RENAME , TRUNCATE  methods.

 *note: Keywords are the reserved word in sql like : CREATE , ALTER,ADD .and we do not use that word to assign the object_name.

 

#DML : Its statement allow us to manipulate the data in the tables of a database.

            It contains : SELECT , INSERT , UPDATE , DELETE statement(methods)

#DCL : It contains the following statement : GRANT & REVOKE.  allow us to manage the rights users have in a database 



The REVOKE clause : used to revoke the permissions and privileges of database users. It exact opposite of GRANT though the syntax are same. 

#TCL : Not every change you make to a database is saved automatically. It contains :

        COMMIT : saves the changes in the database ,  changes can not be undone.

        ROLLBACK :    Allows you to take a step back.

                                the last changes made will not be count

                                 reverts to the last non-commited state

 

    

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