Friday, April 8, 2016

What is an SQL query and introduction of sql query

SQL is a Structured Query Language.  SQL developed by  IBM in 1970 by Donald D. Chamberlin and Raymond F. Boyce. programming language  (SQL ) designed for managing data held in a relational database management system (RDBMS).There are different  type of  software use for SQL language . SQL  is simple  and powerful  language used to create , update, manipulate data  in a system. Now a days most popular  database software are Oracle,Xampp,Wamp,Lamp,SQLite, MS Server  .

SQL  statement  categories  are DDL,DML,DCL

DDL Statements:

Create :        Use for create objects  in the database.
Alter :          Alter the structure  of database object.
Drop :          Drop use for database .
Truncate :     Remove all record from a table.
Grant:          Assigning privileges.

DML Statements:

Select:       Select data from the table or database.
Insert:        It is used to insert data into a table.
Update:      Update data from table.
Delete:       Use for delete column and rows.

DCL Statements:

Commit:       It make  current transaction  permanent .
Savepoint :    It will identify  a point in a  transaction for rollback.
Rollback:      Undo all the changes in current transaction .
Set:              Used to define the properties of transaction.

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