Question

What type of join is needed when you wish to include rows that do not have matching values?

Answer 1

Answer:  Outer join

Explanation:OUTER JOIN is the only join which shows the unmatched rows.

Answer 2

An outer join is needed when you wish to include rows that do not have matching values. In fact, an outer join is the only way to represent unmatched values.

The results of left and right outer joins, in SQL, are combined by a full outer join which returns all rows from the tables on both the sides of the join clause.