Question

Which function returns NULL if expr1 = expr2?

(a) CASE

(b) IF()

(c) IFNULL()

(d) NULLIF()

I had been asked this question during a job interview.

I would like to ask this question from Functions topic in portion Data Type Reference, Operators and Functions of MySQL

Answer 1

Right option is (d) NULLIF()

The explanation: The ‘CASE’ is used for the case operator. The function ‘IF()’ is used for the if/else construct. The function ‘IFNULL()’ is the Null if/else construct. ‘NULLIF()’ returns NULL if expr1 = expr2.