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 SQL Server. This had lead to lots of confusion over time, and this is the best way that I have seen to describe them.
Version 4 of the poster contains 3 new Venn diagrams, INTERSECT, UNION, and EXCEPT. This caused the poster to need to be split onto 2 pages.
If you are looking for the MySQL version of the poster, click here.
Click to download the TSqlJoinTypePoster.pdf
The diagram shows the following: INNER JOIN, LEFT OUTER JOIN, RIGHT OUTER JOIN, SEMI JOIN, ANTI SEMI JOIN, LEFT OUTER JOIN with exclusion, RIGHT OUTER JOIN with exclusion, FULL OUTER JOIN, CROSS JOIN, FULL OUTER JOIN with exclusion, CROSS APPLY, OUTER APPLY, two INNER JOINs, two FULL OUTER JOINs, INNER JOIN and a LEFT OUTER JOIN, two LEFT OUTER JOINs, INTERSECT, UNION, and EXCEPT.
If you are interested in printing out the poster, download the TSqlJoinTypePoster.pdf file and print it.