Answer: Outer join

The question asks which join type returns all rows from one table, even if there are no matching rows in the other table. This is the definition of an OUTER JOIN. In SQL, outer joins (LEFT OUTER JOIN, RIGHT OUTER JOIN, or FULL OUTER JOIN) preserve all rows from one or both tables, including those without matches. The community discussion shows 100% consensus on answer D (Outer join) with multiple users confirming this is correct and upvoted explanations. Cross join (A) produces a Cartesian product of all rows from both tables. Inner join (B) returns only matching rows from both tables. Natural join (C) is a type of inner join that matches columns with the same name, so it also requires matches.

Author: LeetQuiz Editorial Team