Question

7. Which SELECT statement implements a self join?

SELECT item.part_id, type.product_id
FROM part item JOIN product type
ON item.part_id =! type.product_id;
SELECT item.part_id, type.product_id
FROM part item JOIN product type
ON item.part_id = type.product_id;
SELECT item.part_id, type.product_id
FROM part item JOIN part type
ON item.part_id = type.product_id;
SELECT item.part_id, type.product_id
FROM part item JOIN product type
ON item.part_id = type.product_id (+);​

Answer 1

SELECT item.part_id, type.product_id

FROM part item JOIN part type

ON item.part_id = type.product_id;

Step-by-step explanation:

A self join is when a table joins to itself, in the above answer the part joins itself, note in bold below

FROM part item JOIN part type