[Solved] What will be the output of this query?WITH numbers AS (SELECT generate_series(1,3) AS num) SELECT num, num * num AS square FROM numbers; | PostgreSQL

PostgreSQL - Common Table Expressions

What will be the output of this query?

WITH numbers AS (SELECT generate_series(1,3) AS num) SELECT num, num * num AS square FROM numbers;

AEmpty result set

BAn error because generate_series cannot be used in CTE

COnly one row with num=3 and square=9

DRows with numbers 1 to 3 and their squares: (1,1), (2,4), (3,9)

Step-by-Step Solution

Solution:

Step 1: Understand generate_series function in CTE
generate_series(1,3) produces rows with values 1, 2, and 3.
Step 2: Calculate squares in main query
The main query selects each number and its square, so output is (1,1), (2,4), (3,9).
Final Answer:
Rows with numbers 1 to 3 and their squares: (1,1), (2,4), (3,9) -> Option D
Quick Check:
generate_series in CTE works = D [OK]

Quick Trick: generate_series can be used inside CTEs to create sequences [OK]

Common Mistakes:

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What will be the output of this query?