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First 2 free Intermediate SQL

SQL – Indexes

Practice SQL index interview questions. Cover when to create indexes, types of indexes, and performance trade-offs. Answer questions and receive feedback on correctness and approach. Ideal for intermediate SQL interview prep. First 2 questions are free with full feedback.

  • Level Intermediate
  • Questions 12
  • indexes

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Sample sql – indexes interview questions

Preview 6 questions from this track in quiz order. In the full quiz you answer one at a time — type or speak — then get a score and feedback.

  1. What is a database index?

    What a strong answer includes

    Structure that speeds up data retrieval.

  2. When should you create an index?

    What a strong answer includes

    Columns used in WHERE, JOIN, or ORDER BY.

  3. What are the downsides of indexes?

    What a strong answer includes

    Slower writes and extra storage.

  4. Explain a composite index.

    What a strong answer includes

    Index on multiple columns.

  5. What is the difference between a clustered and non-clustered index?

    What a strong answer includes

    Clustered determines row order; non-clustered is separate.

  6. How do you decide the order of columns in a composite index?

    What a strong answer includes

    Most selective or most frequently filtered first.