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

PostgreSQL - Aggregate Functions and GROUP BY

Given the table sales with columns region, product, and amount, what will be the output of this query?

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

ASum of amounts for each product

BSum of amounts for each region

CSum of amounts for each region and product

DTotal sum of all amounts without grouping

Step-by-Step Solution

Solution:

Step 1: Analyze the GROUP BY clause
The query groups rows by region, so aggregation applies per region.
Step 2: Understand the aggregation function
SUM(amount) calculates the total amount for each group, here each region.
Final Answer:
Sum of amounts for each region -> Option B
Quick Check:
GROUP BY region with SUM = sum per region [OK]

Quick Trick: GROUP BY column aggregates per group [OK]

Common Mistakes:

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Given the table sales with columns region, product, and amount, what will be the output of this query?