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NULLIF

Description​

Returns NULL if the two input values are equal; otherwise, returns the first input value. This function is equivalent to the following CASE WHEN expression:

CASE
WHEN <expr1> = <expr2> THEN NULL
ELSE <expr1>
END

Syntax​

NULLIF(<expr1>, <expr2>)

Parameters​

ParameterDescription
<expr1>The first input value to compare.
<expr2>The second input value to compare against the first.

Return Value​

  • Returns NULL if <expr1> is equal to <expr2>.
  • Otherwise, returns the value of <expr1>.

Examples​

SELECT NULLIF(1, 1);
+--------------+
| NULLIF(1, 1) |
+--------------+
| NULL |
+--------------+
SELECT NULLIF(1, 0);
+--------------+
| NULLIF(1, 0) |
+--------------+
| 1 |
+--------------+