Data blending is a method through which different sources of data are mixed together from multiple sources and then that combined data is sent for data visualization.
Left join is used in data blending in Tableau for combining data. When this join is used a query is sent to the database, where this join would happen. If you are someone who happens to aim for certification in Tableau, then I would recommend you to take up the Tableau certification course from Intellipaat. And in addition to that, check out our Tableau tutorial and if you like to watch a video, then have a look at our YouTube video on Tableau training from our experts to get a better idea.