Update: Tableau 10 is here! Download now to try out the feature outlined below.
You can't always answer your questions with a single data set. Sometimes, to answer your hardest questions, you have to integrate multiple data sets to uncover insight.
That’s why I am so excited about cross-database joins, a new feature in Tableau 10. Let me show you why this feature can be so powerful.
First, I’ll connect to a database on SQL Server to access Seattle overnight-rental data.
With this data set, I can quickly build vizzes which show all the listings in Seattle, sized and colored by nightly rates:
But what if I want to combine this with my Rental Review data set, which is in MySQL? Before Tableau 10, I could use blending, but then I wouldn’t be able to generate extracts, publish the data source, or use aggregations like MEDIAN(). With cross-database joins, I can now simply add MySQL to the data source.
Back on the data tab, click the “add” link to add other connections to this data source. You’ll notice that a number of the connection types are grayed out. That’s because they aren’t supported for cross-database joins yet. Specifically, you cannot use cross-database joins with these connection types:
- Tableau Server
- Google Analytics
- Microsoft Analysis Services
- Microsoft PowerPivot
- Oracle Essbase
- SAP BW
- Teradata OLAP Connector
I’ll click on MySQL and enter my connection information.
Once the connection is added, you’ll see it appear in the top-left part of the data tab. I’ll double-click to rename the connection:
Now I can just drag the MySQL “reviews” table into the canvas to join:
We color-code each connection so you can distinguish the tables in the join and the columns in the data grid. You can see that I have blue columns from SQL Server and orange columns from MySQL that appear side by side in the data grid! Now you can write row-level calculations using fields from both databases, or even create an extract of this multi-connection data source.
And you’re not restricted to just two connections. You can add as many of the supported connections as your analysis requires. Maybe I want to bring in the regional home-sales information as well. I’ll just drag-and-drop the text file into my data source. Note that the new data columns are colored green:
I’ll go back to the viz window and make a quick map showing zip codes colored by the average price versus average rating:
Then I’ll make another viz showing the distribution of rating reviews by zip code:
In the snapshot, I’ve highlighted Tableau’s home turf, the Fremont neighborhood, and we can see that it has a very healthy number of four-star ratings!
With Tableau 10 and cross-database joins, you can bring together all of your data, explore it in new light, and uncover new insights with just drag and drop. I’ve had a ton of fun mashing up internal data with Tableau 10. Share some of your exciting data combinations on Tableau Public!