Solution:Step 1: Analyze first CTEcte1 returns two rows: 'A' and 'B'.Step 2: Analyze second CTE filtering cte1cte2 selects only rows where letter = 'B', so one row with 'B'.Final Answer:One row with letter = 'B' -> Option CQuick Check:Filtering in second CTE = single row 'B' [OK]

[Solved] Consider this query:WITH cte1 AS (SELECT 'A' AS letter UNION ALL SELECT 'B'), cte2 AS (SELECT letter FROM cte1 WHERE letter = 'B') SELECT * FROM cte2;What is the output? | SQL

SQL - Common Table Expressions (CTEs)

Consider this query:

WITH cte1 AS (SELECT 'A' AS letter UNION ALL SELECT 'B'), cte2 AS (SELECT letter FROM cte1 WHERE letter = 'B') SELECT * FROM cte2;

What is the output?

ASyntax error due to UNION ALL

BTwo rows with letters 'A' and 'B'

COne row with letter = 'B'

DNo rows returned

Step-by-Step Solution

Solution:

Step 1: Analyze first CTE
cte1 returns two rows: 'A' and 'B'.
Step 2: Analyze second CTE filtering cte1
cte2 selects only rows where letter = 'B', so one row with 'B'.
Final Answer:
One row with letter = 'B' -> Option C
Quick Check:
Filtering in second CTE = single row 'B' [OK]

Quick Trick: Filter rows in second CTE by condition on first CTE [OK]

Common Mistakes:

Expecting both rows in output
Thinking UNION ALL causes syntax error
Assuming no rows because of filter

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More SQL Quizzes

Consider this query:

Step 1: Analyze first CTE

Step 2: Analyze second CTE filtering cte1

Final Answer:

Quick Check:

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