I am trying to add a second table to my data connection. My original table has a DateAndTime field. My new table has a Date field. I would like the JOIN clause to be something like: DATE(DateAndTime) = Date. Can I use expressions like this in JOIN clauses or can I only use fields? I tried to add a computed field but that didn't help. I'm guessing that computed fields are on the client side so this makes sense, in a way. I assume I can split the DateAndTime field in the database into a Date and a Time field but I am wondering if there is another solution.
You can set up a data blend using the two fields, but I believe you'll need them to be the same data type in order to use them in a true join in Tableau. You could probably use the Custom SQL option to join them as well, but I'd opt for changing the data types.
I am not an expert, and someone else may have a much better solution so don't take my word as expertise. However, this thread seems to confirm what I'm thinking: http://community.tableau.com/thread/118004?start=0&tstart=0