Which type of JOIN is used to returns rows that do not have matching values?
- Natural JOIN
- Outer JOIN
- EQUI JOIN
- All of the above
1 Answers
Answer:
B. Outer JOIN
Explanation:
OUTER JOIN is the only join that returned the unmatched rows in one or both tables. It can be classified into the following types:
- LEFT JOIN that shows only the unmatched rows from the left table.
- RIGHT JOIN that shows only the unmatched rows from the right table.
- FULL OUTER JOIN that shows the unmatched rows from both tables.
EQUI JOIN shows records for equality or matching column(s) values of the relative tables.
A Natural join can only be performed if at least one common attribute exists between two relations (the attributes should be the same name and domain).