Question

What is the function of the not null constraint?

(a) It prevents illegal data from being entered into the database

(b) It ensures that data is entered into the database

(c) It ensures that the data entered is unique

(d) None of the mentioned

I got this question in homework.

My doubt is from Integrity Constraints in chapter Intermediate and Advanced Sql of RDBMS

Answer 1

The correct answer is (b) It ensures that data is entered into the database

To explain: The not null constraint ensures that data is entered into the database. It displays an error message whenever a data field mentioned is left empty.