ALTER

ALTER

--===================[ALTER]============================================================

--ALTER is used to add or delete new columns to the existing table or to change the datatypes

-- Adds the column telephone_no to the employee table.

ALTER TABLE employee

ADD telephone_no CHAR(12) NULL

SELECT * FROM employee

--chnage the datatype of the column telephone_no

ALTER TABLE employee

ADD telephone_no NVARCHAR(15)

SELECT * FROM employee

--deletes the column telephone_no

ALTER TABLE employee

DROP telephone_no

SELECT * FROM employee