How to use IF condition in mysql query

MySQL IF() takes three expressions and if the first expression is true, not zero and not NULL, it returns the second expression. Otherwise, it returns the third expression.

Depending on the context in which it is used, it returns either numeric or string value.
IF(expression ,expr_true, expr_false);

SELECT 
id, IF(payment_date='1970-01-01 00:00:00', null, payment_date) as payment_date 
FROM `student_detail`