When we want to add,delete and delete the coloum in the exiting table then we use Alter Command.

When we want to add,delete and delete the coloum in the exiting table then we use Alter Command.

Add a Column in a Table
Syntex:

ALTER TABLE tableName
ADD columnname datatype

Example:

ALTER TABLE Emp
ADD City Varchar(500) null

Add More than one colum at a time:

ALTER TABLE Emp
ADD (City Varchar(500) null,Country Varchar(500) null)

Delete a colum from the Table
Syntex:

ALTER TABLE tableName
DROP COLUMN columnname

Example:

ALTER TABLE Emp
DROP COLUMN City

Change datatype of Column.
Syntex:

ALTER TABLE tableName
Alter COLUMN columnname datatype

Example:

ALTER TABLE Emp
Alter COLUMN City nvarchar(400)