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What is the use of MySQL NULLIF() control flow function?

MySQL NULLIF() control flow function will return NULL if both the arguments are the same, otherwise, it returns the first argument.

Syntax

NULLIF(expression1, expression2)

Here if expression1 = expression2, NULL will be returned by NULLIF() otherwise expression1 will be returned. Following example will exhibit this −

mysql> Select NULLIF('Ram','Ram');
+---------------------+
| NULLIF('Ram','Ram') |
+---------------------+
| NULL                |
+---------------------+
1 row in set (0.00 sec)

mysql> Select NULLIF('Ram','Shyam');
+-----------------------+
| NULLIF('Ram','Shyam') |
+-----------------------+
| Ram                   |
+-----------------------+
1 row in set (0.00 sec)