IFNULL
function is one of the MySQL control flow functions that accepts two arguments and returns the first argument if it is not NULL
. Otherwise, the IFNULL
function returns the second argument.
The two arguments can be literal values or expressions.
The following illustrates the syntax of the IFNULL
function:
IFNULL(expression_1,expression_2);
Example:
-
SELECT IFNULL(1,0); -- returns 1
-
SELECT IFNULL('',1); -- returns ''
-
SELECT IFNULL(NULL,'IFNULL function'); -- returns IFNULL function
How it works.
-
IFNULL(1,0)
returns 1 because 1 is notNULL
. -
IFNULL(' ',1)
returns' '
because the' '
string is notNULL
. -
IFNULL(NULL,'IFNULL function')
returnsIFNULL function
string because the first argument isNULL
.