Scalar function
Aliases: ifnull
Returns replacement when value is NULL; returns NULL when both values are NULL.
Syntax
Scalar
- All result alternatives must have compatible types. Matching types are preserved; mixed types may be converted to a common type. Use explicit casts to choose the result type.
Arguments
Returns
- Type: Common SQL type after conversion of value and replacement
- NULL behavior: Returns replacement when value is NULL; returns NULL when both values are NULL.
Properties
Usage notes
- IFNULL requires compatible same-type arguments. Use explicit casts when the two arguments have different types.
- INTEGER and INT mean the same type; STRING means VARCHAR text. NULL can be used with a supported type. Cast NULL explicitly when its type would otherwise be unclear.
- Query tools may report a DECIMAL result as DOUBLE or a TIME result as INTEGER. The returned value still keeps its decimal precision and scale, or its time type. A reported type does not convert the value.
- Deterministic: The same inputs and settings produce the same result.
Examples
Typical behavior
Supply a string default
In the result table, '' denotes an empty string.
Limitations
- The two arguments must admit a common type.
Last modified on October 15, 2026
