Categories:
Conditional Expression Functions

NULLIF

Returns NULL if expr1 is equal to expr2, otherwise returns expr1.

Syntax

NULLIF( <expr1> , <expr2> )

Arguments

expr1
Any general expression of any data type.
expr2
Any general expression that evaluates to the same data type as expr1.

Returns

The data type of the returned value is the data type of expr1.

Collation Details

  • The collation specifications of all input arguments must be compatible.
  • The collation of the result is the same as the collation of the first input.

Examples

SELECT a, b, NULLIF(a,b) FROM i;

--------+--------+-------------+
   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]      |
--------+--------+-------------+