Databases · Junior · Question 14 of 75

What does `WHERE email = NULL` return?

1Rows where email is NULL
✓Correct answer: No rows: comparing with NULL gives NULL, not true; use IS NULL
3Rows where email is empty

Explanation

NULL means 'unknown', so NULL = NULL is also unknown. Use IS NULL / IS NOT NULL, or IS DISTINCT FROM for NULL-safe comparison.

Further reading

PostgreSQL: Comparison operators and NULL ↗

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