One of the beauties of Tableau is the ease with which one can connect to many different data sources in various ways. As mentioned earlier in this book, there are 70 connectors defined in Tableau 2018.3 for interfacing with a variety of data sources. Furthermore, this flexibility extends beyond simply connecting to single tables or files. Previous versions of Tableau accommodated joining within data sources and data blending disparate data sources. Since Tableau 10, it can even accommodate cross-joining data sources, and with Tableau 2019.1 you will be able to join published datasources on Tableau Server.
Although Tableau makes it easy to connect to various data sources, it should be stressed that Tableau is not an Extract, Transform, and Load tool. If complex joins and complex data blending are required to generate useful results...