CHECK CONSTRAINT
The CHECK constraint is used to limit the value range that can be placed in a column.
The CHECK constraint allows only certain values for a column.
How to create a CHECK constraint?
Check constraint can be created in this way:
CREATE TABLE Student(
RollNumber INT NOT NULL,
Name varchar(255),
Age INT,
CHECK (Age>=18)
);
How to delete a CHECK constraint?
ALTER TABLE Student DROP CHECK Age;