<expression1> if it’s non-NULL, otherwise returns <expression2>.
Syntax
Parameters
Return Types
Same as input typeRemarks
UseZEROIFNULL(<expression>) as a synonym shorthand for IFNULL(<expression>, 0).
IFNULL(a, b) has the same behaviour as COALESCE(a, b).
Examples
The following example shows the core behavior:IFNULL returns the original value when it is non-NULL, and returns the replacement when it is NULL:
Rows: 5Execution time: 4.15ms
IFNULL to replace the nextlevel value with 0 for the final level in the levels table, which has no next level (NULL):
Rows: 10Execution time: 6.00ms