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Interview quiz track

First 2 free Junior SQL

SQL – UNION and Set Operations

Practice SQL UNION and set operation interview questions. Cover UNION, UNION ALL, INTERSECT, and EXCEPT. Write queries and receive feedback on correctness and approach. Ideal for beginner SQL interview prep. First 2 questions are free with full feedback.

  • Level Junior
  • Questions 12
  • UNION
  • set operations

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Sample sql – union and set operations 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 the difference between UNION and UNION ALL?

    What a strong answer includes

    UNION removes duplicates; UNION ALL keeps them.

  2. Write a query that combines customer names from two tables.

    What a strong answer includes

    Uses UNION or UNION ALL correctly.

  3. When would you use UNION ALL instead of UNION?

    What a strong answer includes

    When duplicates are acceptable or performance matters.

  4. What rules apply when using UNION?

    What a strong answer includes

    Same number of columns and compatible types.

  5. Explain INTERSECT.

    What a strong answer includes

    Returns rows common to both queries.

  6. Explain EXCEPT (or MINUS).

    What a strong answer includes

    Returns rows in the first query but not the second.