In Tableau Public there is a limited amount of data sources you can utilise. There are many more in the paid desktop product, where you can connect to files such as Microsoft Excel and Text files (csv, txt).

Data connections are always indicated by the colour blue, so look for the blue menu or the blue Connect to Data link if you aren’t sure where to start. There is also a Data drop down menu to select from. You should then select your file type, for example Microsoft Excel and browse to the file location.

                

| Image: Tableau menu |

Tableau Public is designed for working with unencrypted data sources. If you do not have any data sources that can be unencrypted for use, search on your browser for Tableau Public resources / sample data. You will find data sets about topics including Entertainment, Sports, Business and Education easy to use.

You also have the opportunity to bring in additional data sources and relate them in an easy, visual way.

In order to successfully relate two data sources, you need to know:

• Which field(s) do these data sources have in common? This field will normally be named the same and will always have the same data type. It is important that this column means the same thing in both data sources.

• Are these two data sources at the same level of granularity? Granularity refers to how detailed the data is or how detail-orientated a single record in that data set is.

As an example, consider what would happen if you compared daily Sales transactions and total Sales targets for each salesperson.

Fortunately, in Tableau you can work with Relationships which retain the granularity of each table individually and allows you to relate the data through a logical layer, connecting on something like employee ID, to aggregate the sales transactions per month against the sales target per employee.

| Image: Relationship successfully created on a shared field|

The orange line indicates a relationship has been successfully created on a shared field (Employee ID) which has the same data type. This works even though the Sales table has thousands of rows and the Employee table just nine rows, one for each salesperson.

Next, let’s see how you can use Tableau to filter data.