NULLIF

The NULLIF() function compares two expressions and returns NULL if they are equal. Otherwise, the first expression is returned.

tip

Before using this function, you must enable the new Databend planner. To do so, perform the following command in the SQL client:

> set enable_planner_v2=1;

Syntax

IF( <expr1>, <expr2>)

Arguments

Arguments	Description
<expr1>	Any general expression of any data type.
<expr2>	Any general expression that evaluates to the same data type as \<expr1>.

Return Type

The data type of the returned value is the data type of \<expr1>.

Examples

SET enable_planner_v2 = 1;

SELECT a, b, NULLIF(a, b) FROM t;
+------+------+--------------+
| a    | b    | NULLIF(a, b) |
+------+------+--------------+
|    0 |    0 |         NULL |
|    0 |    1 |            0 |
|    0 | NULL |            0 |
|    1 |    0 |            1 |
|    1 |    1 |         NULL |
|    1 | NULL |            1 |
| NULL |    0 |         NULL |
| NULL |    1 |         NULL |
| NULL | NULL |         NULL |
+------+------+--------------+