Usage and Examples of SQL ALTER TABLE Keywords

SQL Keyword Reference

ALTER TABLE

The ALTER TABLE command adds, deletes, or modifies columns in the table.

The ALTER TABLE command can also add and delete various constraints in the table.

The following SQL statement adds the 'Email' column to the 'Customers' table:

　　ALTER TABLE Customers
ADD Email varchar(255);

The following SQL statement deletes the 'Email' column from the 'Customers' table:

　　ALTER TABLE Customers
DROP COLUMN Email;

SQL Keyword Reference