SQL Alter Table - Adding a column to existing table

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SQL ALTER TABLE statement is used to modify or change the structure of the table. By using this ALTER TABLE, you can add, delete or modify the column of the existing table.

SQL ALTER TABLE ADD column - Syntax

1. The following syntax is used to add new column into the existing table.

   ALTER TABLE  table-name ADD column-name data-type;
   

   Following is the example SQL query to add a new column [dept] into [student] table.

   
   mysql> ALTER TABLE student ADD Dept char(10);
   Query OK, 0 rows affected (1.55 sec)
   Records: 0  Duplicates: 0  Warnings: 0
   
   

   
   
   mysql> desc student;
   +--------+-------------+------+-----+---------+-------+
   | Field  | Type        | Null | Key | Default | Extra |
   +--------+-------------+------+-----+---------+-------+
   | RollNo | int         | YES  |     | NULL    |       |
   | Name   | varchar(20) | YES  |     | NULL    |       |
   | Age    | int         | YES  |     | NULL    |       |
   | City   | char(20)    | YES  |     | NULL    |       |
   | Dept   | char(10)    | YES  |     | NULL    |       |
   +--------+-------------+------+-----+---------+-------+
   5 rows in set (0.14 sec)
   

   
   

   ALTER TABLE DROP COLUMN

   ALTER TABLE MODIFY column type and other attributes

   ALTER TABLE CHANGE existing-column-name new-column-name

   
   
   

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