Alter Keyword with example

Use of Alter Keyword

Syntax : Alter Table Table_name ADD column_name datatype Example : Consider the following table Table: Salary

Emp_id	Emp_name	Emp_reg	Emp_salary
01	chandan	E_01	25000
02	adhiraj	E_02	30000
03	raghu	E_03	35000
04	raghunath	E_04	36000
05	Alax	E_05	40000

and it is required to add new column(city) in table then we will use alter keyword Query : Alter table Salary ADD column city varchar(50) Result:

Emp_id	Emp_name	Emp_reg	Emp_salary	city
01	chandan	E_01	25000	Null
02	adhiraj	E_02	30000	Null
03	raghu	E_03	35000	Null
04	raghunath	E_04	36000	Null
05	Alax	E_05	40000	Null

Query to update column datatype :

In Mysql : ALTER TABLE table_name MODIFY COLUMN column_name datatype In sql : ALTER TABLE table_name ALTER COLUMN column_name datatype

Query to drop a column in Table

Syntax : ALTER TABLE tablename DROP COLUMN columnname Example : ALTER TABLE tablename DROP COLUMN city Now column city will be droped from table salary

Tag :Alter keyword with example, use of alter keyword in SQL