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First 2 free Junior SQL

SQL – NULL Handling

Practice SQL NULL handling interview questions. Cover IS NULL, COALESCE, NULL in aggregations, and common pitfalls. 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
  • NULL

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Sample sql – null handling 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. How do you check if a value is NULL in SQL?

    What a strong answer includes

    Uses IS NULL, not = NULL.

  2. What is the difference between NULL and an empty string?

    What a strong answer includes

    NULL means unknown; empty string is a value.

  3. How do you replace NULL with a default value?

    What a strong answer includes

    Uses COALESCE or IFNULL.

  4. Write a query to find rows where email is NULL.

    What a strong answer includes

    Uses IS NULL.

  5. How do aggregate functions treat NULL?

    What a strong answer includes

    Most ignore NULL (except COUNT(*)).

  6. Why does WHERE column = NULL not work?

    What a strong answer includes

    NULL comparisons return unknown.