Conditional Functions

Function	Description	Example	Result
IF(cond1, expr1, [cond2, expr2, ...], expr_else)	If cond1 is TRUE, it returns expr1. Otherwise if cond2 is TRUE, it returns expr2, and so on.	IF(1 > 2, 3, 4 < 5, 6, 7)	6
IFNULL(expr1, expr2)	Return expr1 if it is not NULL. Otherwise return expr2. They must have the same data type.	IFNULL(0, NULL)	0
value [ NOT ] IN (value1, value2, ...)	Check whether value is (or is not) one of the members of an explicit list.	1 not in (2, 3)	1(TRUE)
expr1 IS [ NOT ] DISTINCT FROM expr2	Compares whether two expressions are equal (or not equal) with awareness of nullability, meaning it treats NULLs as known values for comparing equality.	NULL is distinct from NULL	0(FALSE)
IS_NOT_NULL(expr)	Check whether the value is not NULL.	IS_NOT_NULL(1)	1(TRUE)
IS_NULL(expr)	Check whether the value is NULL.	IS_NULL(1)	0(FALSE)
NULLIF(expr1, expr2)	Return NULL if two expressions are equal. Otherwise return expr1. They must have the same data type.	NULLIF(0, NULL)	0