DataBase - DDL

DDL Stands for Data Definition Language

create statement

     The CREATE TABLE statement is used to create a table in a database.

  syntax:

         CREATE TABLE table_name

(

column_name1 data_type,

column_name2 data_type,

column_name3 data_type,

....

)

 Eg. create table employee(empno int,name varchar(30),desg char(3),salary int)

Alter statement

   The ALTER TABLE statement is used to add, delete, or modify columns

    in an existing table.

To add a column in a table, use the following syntax:

Syntax :ALTER TABLE table_name ADD column_name datatype

To delete a column in a table, use the following syntax

Syntax : ALTER TABLE table_name DROP COLUMN column_name

To change the data type of a column in a table, use the following syntax:

Syntax ALTER TABLE table_name ALTER COLUMN column_name datatype

Drop statement

    The DROP TABLE statement is used to delete a table.

syntax:

DROP TABLE table_name

The DROP DATABASE statement is used to delete a database.

syntax:

DROP DATABASE database_name