PostgreSQL - Window Functions in PostgreSQL
Which window function calculates the average value over a set of rows without collapsing the result into a single row?
Which window function calculates the average value over a set of rows without collapsing the result into a single row?
easy📝 Conceptual Q2 of 15
Step-by-Step Solution
Solution:
Step 1: Identify AVG() OVER() behavior
AVG() OVER() calculates the average for each row over a window without grouping rows into one.Step 2: Contrast with aggregate AVG()
Aggregate AVG() returns a single average value for all rows, collapsing them.Final Answer:
AVG() OVER() -> Option DQuick Check:
AVG() OVER() = Average per window row [OK]
Quick Trick: Use OVER() to keep row details while averaging [OK]
Common Mistakes:
- Using AVG() without OVER() expecting row-wise averages
- Confusing SUM() with AVG()
- Assuming COUNT() calculates averages
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