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Explain CTE vs Temp Table. What are the differences and use cases?

SQLmedium0.5 min readPremium

**Architectural Logic**: CTE = inline; temp table = materialized—affects performance and reuse. **CTE**: Scope within query; no persistence; optimizer may inline. **Temp Table**: Materialized; session scope; can index; statistics available. **Use CTE**: One-off logic;...

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Frequency
Low
Asked at 1 company
Category
487
questions in SQL
Difficulty Split
130E|271M|86H
in this category
Total Bank
1,863
across 7 categories
Asked at these companies
Fractal
Key Concepts Tested
join

Why This Question Matters

This medium-level SQL question appears frequently in data engineering interviews at companies like Fractal. While less common, it tests deeper understanding that distinguishes strong candidates. Mastering the underlying concepts (join) will help you answer variations of this question confidently.

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Expert Answer
100 words

Architectural Logic: CTE = inline; temp table = materialized—affects performance and reuse. CTE: Scope within query; no persistence; optimizer may inline. Temp Table: Materialized; session scope; can index; statistics available. Use CTE: One-off logic; readability; recursion. Use Temp Table: Multiple references; large intermediate; need indexes. Example: CTE for single-use subquery; temp table for CREATE TEMP TABLE t AS ...; CREATE INDEX ON t(col); then multiple joins. Scalability: Temp table enables index; CTE may duplicate work. Cost: Temp table has storage cost; CTE is compute-only within query. Best Practice: CTE for simplicity; temp table for performance with reuse; check query plan.

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