Databases · Junior · Question 59 of 75

What does `COALESCE(nickname, name)` return?

1Both values joined together
2NULL if either value is NULL
✓Correct answer: nickname if it's not NULL, otherwise name

Explanation

COALESCE returns the first non-NULL argument. It's handy for defaults, e.g. COALESCE(SUM(amount), 0) when there are no rows.

Further reading

PostgreSQL: Comparison operators and NULL ↗

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