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Asked 2 years ago
12 May 2021
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Eusebio

Eusebio posted

Can we use NVL in group by?

Can we use NVL in group by?
kord

kord
answered Feb 25 '23 00:00

No, the NVL function cannot be used in a GROUP BY clause directly in SQL . The GROUP BY clause is used to group the result set by one or more columns in the query, and it operates on the original columns in the table or the derived columns in the query, not on the expressions or functions.

However, you can use the NVL function in the select clause of the query to replace null values with a default value or a specific value , and then use the resulting expression in the GROUP BY clause.

Here's an example of using the NVL function in the select clause with GROUP BY:


SELECT NVL(category, 'Unknown') AS category, COUNT(*) AS total
FROM products
GROUP BY NVL(category, 'Unknown')


In this example, the NVL function is used to replace null values in the category column with the string 'Unknown'. The resulting expression is used in the GROUP BY clause to group the products by category, including the ones with null values.

Note that the syntax and behavior of the NVL function may vary depending on the database system you are using. Some databases may use a different function name or syntax to achieve the same result.
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