Databases · Junior · Question 13 of 75

What does `SELECT DISTINCT city FROM users` return?

1Only cities with exactly one user
2The number of cities
✓Correct answer: Each city once, without duplicates

Explanation

To count unique values use COUNT(DISTINCT city). PostgreSQL also has DISTINCT ON (...) to keep the first row per group.

Further reading

PostgreSQL: SELECT ↗

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