Not only can you connect to an Excel sheet in Tableau but you can connect to different databases. This of course means you need to have the correct driver installed for said database.
I am a big advocate for educating employees in the workplace and there is a cost for NOT doing so. With all of the advances in AI at the workplace, you still need to educate users on how to use it. I am going to provide a hypothetical situation for better understanding for education with connecting to a database in Tableau.
Let's say you are a developer on a team and you received a workbook from someone else that you have to make updates on. The workbook is connecting to a database. You publish the workbook with your changes to the Tableau server. Then you get an email from your technology team that they terminated your query as it was scanning the entire database and bogging down the server. What happened?
You look at the query in the workbook and notice its a very simple SQL query. It is missing a PARTITION BY statement, nor does it have a GROUP BY statement. This is causing the query to scan the entire database. This slows down the server for everyone. You MUST put one of these statements in. GROUP BY normally reduces the number of rows returned by rolling them up and calculating averages or sums for each row. PARTITION BY does not affect the number of rows returned, but it changes how a window function's result is calculated.
Side Note: A great place to go to learn SQL if you don't know it is w3schools.com. It has fields in the webpage where you can test out code. You can also learn other languages in their website. I picked up html from there. However, It does not have the PARTITION BY statement. I found this in Stackoverflow which is another great place to find information.
This is just part of the issue. You have Tableau pulling the data behind the scenes. You also have your visualizations on top of this data pull. If your data pull takes forever, that's part of the problem! Tableau then has to render your visualizations on top of this! This can cause your dashboard to perform slowly on the server and it will cause a poor customer experience.
What are the costs of this issue? Time of course. How many other users need to connect to that database? Are you impacting their workday and their analyses?
What if there is an audit and legal needed information from that database? Will this cause an expensive delay?
w3schools.com is also FREE so is Stackoverflow.
It is important to empower yourself with a commitment to learn new things. If you are a manager, you are helping to drive a successful culture if you encourage your employees to educate themselves. You are also setting the steps for your employees to be self-sufficient. There are lots of articles on the way you should encourage training, here is a great one from Harvard Review: