Because I wasn't sure, looked online and found an example using left outer joins, that joined three tables like that, i.e. where table 1 was related to table 2, table 2 was related to table 3, but table 3 was not related to table 1.
This is exactly why I get unsure about this stuff - because I can find an example that seems to work, and its still wrong!
Edit: OK, that's weird - I tried just regular inner joins now, and it seems to work. I was sure that was the first thing I tried at least 9 out of 10 times I use SQL queries I just use inner joins.