The NULLIF function takes two arguments. If the two arguments are equal, then NULL is returned. Otherwise, the first argument is returned. The syntax for NULLIF is as follows:
NULLIF ("expression 1", "expressions 2")
It is the same as the following CASE statement:
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SELECT CASE ("column_name")
WHEN "expression 1 = expression 2 " THEN "NULL"
[ELSE "expression 1"]
For example, let's say we have a table that tracks actual sales and sales goal as below:
We want to show NULL if actual sales is equal to sales goal, and show actual sales if the two are different. To do this, we issue the following SQL statement:
SELECT Store_Name, NULLIF (Actual, Goal) FROM Sales_Data;
|Store_Name||NULLIF (Actual, Goal)|
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