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SQL · PRACTICAL GUIDE

CTE vs Subquery

Choose between a named intermediate result and an inline nested query.

Practice SQLLearning path

What this solves

Build a readable multi-step supplier price analysis. This pattern is useful when the business question is clear but a generic tutorial is too abstract.

The rule

Use a CTE when naming the intermediate logic makes the query easier to inspect or reuse.

WITH PriceChange AS (
 SELECT SKU, NewPrice-OldPrice AS Delta FROM Prices
)
SELECT * FROM PriceChange WHERE Delta>0;

Real-work checklist

  1. Define the business key and expected grain before writing the formula, query or markup.
  2. Test the pattern on a small known sample where you can verify the answer manually.
  3. Check missing values, duplicates and data types before trusting a large result.
  4. Scale to the real file or database only after the logic is proven.

Common mistake

A CTE is mainly a readability and organization tool; it is not automatically faster.

Try it next

PracticeChange the example and verify the result.Use a toolMove from a small example to real work.Related contentFind guides, errors and scenarios on this topic.