JOIN Check In

INNER JOINs

Notice every JOIN we have done up to this point has been an INNER JOIN. That is, we have always pulled rows only if they exist as a match across two tables.

Our new JOINs allow us to pull rows that might only exist in one of the two tables. This will introduce a new data type called NULL. This data type will be discussed in detail in the next lesson.

Quick Note

You might see the SQL syntax of

LEFT OUTER JOIN

OR

RIGHT OUTER JOIN

These are the exact same commands as the LEFT JOIN and RIGHT JOIN we learned about in the previous video.

OUTER JOINS

The last type of join is a full outer join. This will return the inner join result set, as well as any unmatched rows from either of the two tables being joined.

Again this returns rows that do not match one another from the two tables. The use cases for a full outer join are very rare.

You can see examples of outer joins at the link here and a description of the rare use cases here. We will not spend time on these given the few instances you might need to use them.

Similar to the above, you might see the language FULL OUTER JOIN, which is the same as OUTER JOIN.