PostgreSQL - Common Table Expressions
Which of the following is the correct syntax to combine the anchor and recursive parts in a recursive CTE?
Which of the following is the correct syntax to combine the anchor and recursive parts in a recursive CTE?
easy📝 Syntax Q3 of 15
Step-by-Step Solution
Solution:
Step 1: Recall recursive CTE syntax
The anchor and recursive parts are combined using UNION ALL to include all rows, including duplicates if any.Step 2: Identify correct set operator
UNION removes duplicates, but recursive CTEs require UNION ALL to avoid losing rows during recursion.Final Answer:
SELECT * FROM cte_name WHERE condition UNION ALL SELECT * FROM cte_name WHERE condition -> Option BQuick Check:
Recursive CTE uses UNION ALL [OK]
Quick Trick: Use UNION ALL to combine anchor and recursive parts [OK]
Common Mistakes:
- Using UNION instead of UNION ALL
- Using INTERSECT or EXCEPT incorrectly
- Omitting UNION ALL clause
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