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CTEs vs Temp Tables: Which Should You Use?

SQL Mastery Team
March 16, 2026
5 min read

It's **Day 54**, and we're looking at architectural choices. Both CTEs and Temp Tables (`CREATE TEMP TABLE`) store data temporarily. But they are NOT the same.

The Difference

  • **CTE**: Lives only for the duration of a **single query**. It's usually "Virtual" (the database doesn't actually write it to disk).
  • **Temp Table**: Lives and stays in memory/disk until your **database session ends**. You can run 50 queries against it.

    • When to use a CTE

  • When the query is simple/medium complexity.
  • When you only need the data once.
  • When you want your code to be clean and readable.

    • When to use a Temp Table

  • When you have **Millions of rows** and you need to use them in multiple different queries.
  • When you need to add an **Index** to the temporary data to make subsequent steps faster.
  • When your query plan for a CTE is getting "Messy" (the DB is confused about how to optimize it).

    • The Senior Rule

    Start with a CTE. If it gets slow or too complex, "Graduate" it to a Temp Table.

    Your Task for Today

    Think of a scenario where a Temp Table would be better than a CTE (Hint: think about massive data cleaning pipelines).

    *Day 55: CTE Mistakes I See Every Day.*

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