Which of the following is the correct syntax to calculate the cumulative sum of sales ordered by date in PostgreSQL?

easy📝 Syntax Q3 of 15

PostgreSQL - Window Functions in PostgreSQL

ASUM(sales) PARTITION BY date ORDER BY sales

BSUM(sales) OVER (ORDER BY date ROWS UNBOUNDED PRECEDING)

CSUM(sales) GROUP BY date ORDER BY sales

DSUM(sales) OVER (PARTITION BY date ROWS BETWEEN CURRENT ROW AND UNBOUNDED FOLLOWING)

Step-by-Step Solution

Solution:

Step 1: Understand cumulative sum concept
Cumulative sum adds all previous rows up to current row ordered by date.
Step 2: Check window frame syntax
ROWS UNBOUNDED PRECEDING means from first row to current row, correct for cumulative sum.
Final Answer:
SUM(sales) OVER (ORDER BY date ROWS UNBOUNDED PRECEDING) -> Option B
Quick Check:
Cumulative sum uses SUM() OVER with ORDER BY and UNBOUNDED PRECEDING [OK]

Quick Trick: Use ROWS UNBOUNDED PRECEDING for cumulative sums [OK]

Common Mistakes:

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