There are a couple different ways to combine data from different tables. The most common method is an INNER JOIN (shorthand is JOIN) on two rows for where they match up. This will give you an intersection of the two tables. It can be used for one-to-one matching or one-to-many. A LEFT and a RIGHT JOIN will give you the same intersection, but also every record that doesn’t match for whichever side of the JOIN expression you are specifying. For a LEFT JOIN this everything in the FROM statement to the left of the join, and a RIGHT JOIN is to the right. Finally, a FULL JOIN will still return the intersection when the values match, but for all rows that don’t match, the partial output will be available for both tables. Places where there wasn’t a match will output NULL values. All of these JOINs include an intersection of the two tables. If you don’t need that intersection, you likely need to do something other than JOIN.
Inner Joins Outer Joins Full Joins
