[Solved] Given the table sales(product, region, amount), what will be the output of this query?SELECT product, region, SUM(amount) FROM sales GROUP BY GROUPING SETS ((product), (region)); | PostgreSQL

PostgreSQL - Aggregate Functions and GROUP BY

Given the table sales(product, region, amount), what will be the output of this query?

SELECT product, region, SUM(amount) FROM sales GROUP BY GROUPING SETS ((product), (region));

ASum of amounts grouped by product only

BSum of amounts grouped by product and region combined

CSum of amounts grouped by product and sum grouped by region in one result

DSyntax error due to wrong GROUPING SETS usage

Step-by-Step Solution

Solution:

Step 1: Understand GROUPING SETS ((product), (region))
This groups data twice: once by product alone, once by region alone, producing two sets of grouped sums.
Step 2: Analyze output rows
Result will have rows with product and NULL region, and rows with region and NULL product, each showing sum of amounts.
Final Answer:
Sum of amounts grouped by product and sum grouped by region in one result -> Option C
Quick Check:
GROUPING SETS gives multiple groupings combined [OK]

Quick Trick: GROUPING SETS returns all specified groupings combined [OK]

Common Mistakes:

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Given the table sales(product, region, amount), what will be the output of this query?