Understanding the differences between relationships and joins

It was a straightforward path to answering our question of which product had the highest sales using a relationship. If we had used a join, we could have made a left join with the US Sales Transactions table on the left and the Product DB table on the right and gotten the same answer. However, if we had created that join, it would have excluded all the products that did not sell from the product database, so we may not have been able to answer our question about the percentage of products that did not sell. We could have answered this question with a right join but then we wouldn’t have been able to find the incorrect product IDs because they would not have been identified in our join. We could have created a full outer join, but this would have resulted in a lot of null values in our data, which would make analysis more difficult and caused an explosion of our data.

These limitations make relationships such a...