You can modify or drop a check constraint in SQL using the ALTER TABLE statement. To modify a check constraint, you need to drop the existing one and create a new one with the updated condition.

Sometimes we need to add ulterior constraints to the table we define. The ALTER TABLE statement enables us to do this. There are several types of constraints we can add. If we want to ensure that all ...

ALTER TABLE tbl_reg1 ADD email VARCHAR(100) UNIQUE FIRST; -- Adding a new column 'phone' to tbl_reg1 with not null constraint, placed after 'location' ALTER TABLE tbl_reg1 ADD phone VARCHAR(20) NOT ...