Most Publicly Available Datasets Are Already Finalized In A Single Table. How Important Are Showing ‘joins’ In An Entry Level Portfolio?

Hi guys,

I’m currently working on a data analysis portfolio for entry level jobs and everyone always says that knowing SQL and more specifically, joins, are very important skills to know and to demonstrate.

When obtaining datasets whether it would be from kaggle, data publicly available from an official website, extracting data through API’s, or wherever you get your data from, the one thing i’ve noticed is that all the data is usually already put together in a single table. You can take that data and ‘clean’ it (making rows, columns, values consistent prior to analysis, etc.) and so forth.

Few questions:

How can you demonstrate joins however when most public datasets are already put together and finalized? How important are showing joins in a entry level portfolio? Is finding a ready dataset on kaggle for example and writing SQL queries to just answer business related issues (ex: what features are causing retention rates to decrease?) and then visualzing it on tableau for example good enough for entry level roles? Again no joins used since datasets are usually already completed.

Thanks for any help I can get, greatly appreciated!!