PostgreSQL - Window Functions in PostgreSQL
Which window function would you use to calculate a moving average of sales over the last 3 days in PostgreSQL?
Which window function would you use to calculate a moving average of sales over the last 3 days in PostgreSQL?
easy📝 Conceptual Q2 of 15
Step-by-Step Solution
Solution:
Step 1: Identify moving average calculation
Moving average sums values over a sliding window of rows, here last 3 days means current row plus 2 preceding rows.Step 2: Match window frame clause
ROWS BETWEEN 2 PRECEDING AND CURRENT ROW defines a 3-row window for the sum.Final Answer:
SUM(sales) OVER (ORDER BY date ROWS BETWEEN 2 PRECEDING AND CURRENT ROW) -> Option CQuick Check:
Moving average uses SUM() with ROWS frame [OK]
Quick Trick: Use ROWS BETWEEN for moving window sums [OK]
Common Mistakes:
- Using PARTITION BY instead of ORDER BY for moving windows
- Using COUNT() which counts rows, not sums values
- Confusing RANK() with aggregation
Master "Window Functions in PostgreSQL" in PostgreSQL
Want More Practice?
15+ quiz questions · All difficulty levels · Free
Free Signup - Practice All QuestionsMore PostgreSQL Quizzes