easy5 pts · first answer countssqldebugging

Comparing a column to NULL

This query returns zero rows, even though most posts have never been deleted. Why?

SELECT * FROM posts WHERE deleted_at = NULL;

A.NULL must be written in lowercaseB.Comparing anything to NULL with = gives unknown, not true; use IS NULLC.The column needs an index before the planner is allowed to compare it with NULL valuesD.deleted_at must be cast to text first

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