Given the table sales(date, amount) ordered by date, what will the following query return?

medium📝 query result Q13 of 15

PostgreSQL - Window Functions in PostgreSQL

Given the table sales(date, amount) ordered by date, what will the following query return?

SELECT date, amount, SUM(amount) OVER (ORDER BY date RANGE BETWEEN INTERVAL '1 day' PRECEDING AND CURRENT ROW) AS running_sum FROM sales;

ASum of amounts for the current row and 1 row before

BSum of all amounts up to the current row

CSum of amounts for the current date and the previous day

DSum of amounts for the current date only

Step-by-Step Solution

Solution:

Step 1: Understand RANGE BETWEEN with INTERVAL
RANGE BETWEEN INTERVAL '1 day' PRECEDING AND CURRENT ROW includes rows with date values within 1 day before current row's date.
Step 2: Interpret the SUM window function
SUM(amount) will add amounts for rows dated from 1 day before up to current date.
Final Answer:
Sum of amounts for the current date and the previous day -> Option C
Quick Check:
RANGE with INTERVAL sums by date range [OK]

Quick Trick: RANGE with INTERVAL sums values in date/time range [OK]

Common Mistakes:

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