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What is Select vs SelectMany difference?

Updated May 16, 2026

Short answer

Select projects elements; SelectMany flattens nested collections.

Deep explanation

Select returns one-to-one mapping while SelectMany handles one-to-many relationships.

Real-world example

Flattening order lists from users.

Common mistakes

  • Using Select when flattening is required.

Follow-up questions

  • What does Select return?
  • When to use SelectMany?

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