#PreppinData 2024 week covered using join types, in this case to understand which seats aren’t chosen given a seating plan and booking data.

I had a preconceived idea of the solution here, as I’m used to using LEFT OUTER JOIN in SQL and then having a WHERE clause that returns rows where the result from the right hand table IS NULL. So I was expecting to have a join and then a filter in my flow. However, Tableau Prep has some additional join types that let you return entries where there are only values in the left table, only values in the right table, or even a “not inner” join for entries only in the left or right but not in both. I gave the left only option a go and it did the job nicely! Great how you can click on the segment of the venn diagram representation of the join to select the type too.