Tableau Tip: Blending data sets that have different max dates

Fun little problem at work today. Imagine you have four data sources that all have a Date field in common, but they all land in your database at different times. You want a view of the data for the latest date that they all have in common.

Here's a sample of data the represents the situation:


Inside Tableau, these are four different data sources.  I blend them all together onto a single worksheet like this:


What I desire is to only show the data for the latest date that all four data sources have in common, 10/17/2014 in this example. While there might be a more efficient way to perform these calculations, I want to share the approach that I took to solve the problem.

First, I created a calculated field in each data source to get the max date. Note that I've set the table calculation to calculate along Date.


I then added each of these calculations to the view to make sure I was getting the results I wanted.


Sweet! This is exactly what I was hoping for. Next I need to determine which one of these four dates is the minimum and then return the date from that data source. This is the calc I created and it's kinda messy, but it works. Note this I set the calc to compute along Date.

This calc returns 10/17/2014, which is exactly what I was expecting. One more step. I need to create a calculated field to use as a filter in my view so that I only see one row.


I add this to the Filters shelf, set the Compute using to Date and choose True. That's it!


If anyone knows a more efficient way to do this, I'm all ears! Download the workbook here.