Joins and blends
Joining tables and blending data sources are two different ways to link related data together in Tableau. Joins are performed to link tables of data together on a row-by-row basis. Blends are performed to link together multiple data sources at an aggregate level.
Most databases have multiple tables of data that are related in some way. Additionally, Tableau 10 even allows you to join together tables of data across various data connections for many data sources. As we'll see, Tableau makes it easy to join together tables of data relatively easy.
For example, consider tables such as the following:
The primary table is ...