While we at mysqljoin.com want to provide simply and straightforward tutorials which are easy to understand, we love in depth documentation as well. And since relational databases are very complex, a documentation can be much more technical than our tutorials are.
We just came across such a documentation, a very detailed explanation of SQL join types. We felt that we have to share this with our readers. It’s a very nice follow up reading for everybody who’s currently learning about MySQL joins. Beside many interesting facts you’ll find probably the most interesting visualisation of joined tables we’ve ever seen as well as a visualized classification schemes for SQL joins.
There are different classification schemes and different criteria according to what joins are classified. As a result there is a bit mess in the process of understanding them. I haven’t found a nice scheme or even textual description how each one of various classification schemes and join types relates to other. In the following Meta model there is one possible variant of that, however theoreticians probably would break lances around other possible classification schemes. - SQL join types