SQL Constraints Advanced MCQ All Constraint Types Practice Questions

Direction: Choose the correct option

ALTER TABLE employees ADD CONSTRAINT chk_salary CHECK (salary > 0);

What is 'chk_salary'?

A. Index name

B. Column name

C. Table name

D. Constraint name

Direction: Choose the correct option

Can a table have multiple CHECK constraints?

A. No

B. Depends on database

C. Yes

D. Only one

Direction: Choose the correct option

What happens when you try to insert NULL into a NOT NULL column?

A. Error occurs

B. Default used

C. NULL inserted

D. Insert succeeds

Direction: Choose the correct option

How do you drop a constraint?

A. REMOVE CONSTRAINT

B. DROP CONSTRAINT ... FROM

C. DELETE CONSTRAINT

D. ALTER TABLE ... DROP CONSTRAINT

Direction: Choose the correct option

CREATE TABLE users (
    email VARCHAR(100) UNIQUE
);

What happens with duplicate emails?

A. Both inserted

B. Warning only

C. Second insert overwrites first

D. Second insert fails

Quipoin Menu