Given the table sales with columns region and amount, what will the query SELECT region, amount, SUM(amount) OVER (PARTITION BY region ORDER BY amount) AS running_total FROM sales; return?

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PostgreSQL - Window Functions in PostgreSQL

Given the table sales with columns region and amount, what will the query SELECT region, amount, SUM(amount) OVER (PARTITION BY region ORDER BY amount) AS running_total FROM sales; return?

ASum of amount ignoring region and order

BTotal sales amount for all regions combined

CA running total of sales amount per region ordered by amount

DCount of sales per region

Step-by-Step Solution

Solution:

Step 1: Analyze SUM() OVER with PARTITION and ORDER
The query calculates a running total of amount within each region, ordered by amount.
Step 2: Understand output rows
Each row shows region, amount, and cumulative sum of amounts up to that row in the region.
Final Answer:
A running total of sales amount per region ordered by amount -> Option C
Quick Check:
SUM() OVER (PARTITION BY region ORDER BY amount) = Running total per region [OK]

Quick Trick: ORDER BY inside OVER() defines running total order [OK]

Common Mistakes:

Ignoring ORDER BY causing total sum instead of running total
Confusing COUNT() with SUM()
Assuming no partition means total sum

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Given the table sales with columns region and amount, what will the query SELECT region, amount, SUM(amount) OVER (PARTITION BY region ORDER BY amount) AS running_total FROM sales; return?

Step 1: Analyze SUM() OVER with PARTITION and ORDER

Step 2: Understand output rows

Final Answer:

Quick Check:

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