One of the primary ways we combine multiple tables of data in Tableau Prep is with joins! Joins allow us to merge multiple tables of data horizontally on a common key.
One of the things that distinguishes joins in Tableau Prep from Tableau Desktop are all the join types we can create! In Tableau Desktop, we're limited to Left, Right, Inner and Outer joins. In Tableau Prep we have those four options with the addition of Left Unmatched, Right Matched and All Unmatched. Those unmatched join types provide greater flexibility to create customized workflows and identify values which did not match in our join clause.