We usually use JOIN to find the intersection between two different tables. For example, if you want all the orders from the order table who belong to a certain set of customers from the customer table.
This is the most common usage of a JOIN, specifically an INNER JOIN. The results only include the entries that matchup from each table. There are many other situations that you can incorporate a JOIN to solve. Particularly here we are going to talk about using a JOIN to suppress information from one table by using another. Continue reading Using JOIN for Suppression