So many times I have been asked for help with a query, where the question really comes down to the understanding of the difference between INNER and LEFT or RIGHT JOINs. I created this poster a few years ago and I keep it posted on the wall at the office. This way when I am trying to explain JOIN types, I just refer to the poster.

I have created the poster below to help describe JOIN types in My SQL. This had lead to lots of confusion over time, and this is the best way that I have seen to describe them.

If you are looking for the SQL Server version of this poster, click here.

The diagram shows the following: INNER JOIN, LEFT OUTER JOIN, RIGHT OUTER JOIN, LEFT OUTER JOIN with exclusion, RIGHT OUTER JOIN with exclusion, FULL OUTER JOIN, FULL OUTER JOIN with exclusion, two INNER JOINs, two FULL OUTER JOINs, and two LEFT OUTER JOINs.

If there is anything missing, please post a comment, there is room to add more to this poster.

Enjoy,

-Steve Stedman

Here is some of the feedback that I have received:

This is one of the better and more complete posters out there. nice job! Having the code example is really useful too.

Getting Help from Steve and the Stedman Solutions Team

We are ready to help. Steve and the team at Stedman Solutions are here to help with your SQL Server needs. Get help today by contacting Stedman Solutions through the free 30 minute consultation form.