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Introduction
GROUP BY – Recap
ROLLUP
Summary

## Instruction

When using multiple columns inside ROLLUP's parentheses, it's quite easy to get lost among the resulting rows. SQL offers a function that tells you if the column is included in the grouping: GROUPING().

The GROUPING() function takes one column as an argument. It returns a 0 if the column is used in the grouping and a 1 if it is not. Take a look:

SELECT
full_name,
category,
week,
AVG(score) AS avg_score,
GROUPING(full_name) AS F,
GROUPING(category) AS C,
GROUPING(week) AS W
FROM contest_score
GROUP BY
ROLLUP (full_name, category, week);


As you can see, we added three GROUPING() functions in our SELECT clause. Inside the parentheses, we put all columns from the parentheses of ROLLUP. Let's see what the result is.

## Exercise

Run the template query. As you can see, integer numbers appear in the final columns, denoting the grouping level for a given row.