SQL – How To Alter SQL Table?
Table Of Contents:
- What Is Altering A Table?
- Syntax Of Altering A Table.
- Examples Of Altering A Table.
(1) What Is Altering A Table?
The
ALTER TABLEstatement is used to add, delete, or modify columns in an existing table.The
ALTER TABLEstatement is also used to add and drop various constraints on an existing table.
(2) Syntax Of Altering A Table?
Adding A Column:
ALTER TABLE table_name
ADD column_name datatype;Dropping A Column:
ALTER TABLE table_name
DROP COLUMN column_name;Renaming A Column:
ALTER TABLE table_name
RENAME COLUMN old_name to new_name;Modifying Datatype Of A Column:
ALTER TABLE table_name
ALTER COLUMN column_name datatype;(3) Examples Of Altering A Table
Adding A Column:
ALTER TABLE Customers
DROP COLUMN Email;Dropping A Column:
ALTER TABLE Customers
DROP COLUMN Email;Renaming A Column:
ALTER TABLE Customers
RENAME COLUMN Email to Email_ID;Modifying Datatype Of A Column:
ALTER TABLE Customers
ALTER COLUMN Age varchar(65);