What does the nullif function do in Oracle?

The NULLIF function in Oracle is a conditional function that compares two expressions. It returns NULL if the values are equal, otherwise it returns the value of the first expression.

Specific usage:
NULLIF(expression1, expression2)

If the values of expression1 and expression2 are equal, NULL is returned; otherwise, the value of expression1 is returned.

This function is particularly useful when dealing with situations that may result in a division by zero error. For example, when the divisor is 0, you can use the NULLIF function to avoid the divide by zero error.

For example:
SELECT NULLIF(10, 5) FROM dual;
The result is 10, because 10 is not equal to 5.

The result is NULL because 10 is equal to 10.