From the course: Learning Data Analytics: 1 Foundations

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Understanding joins

Understanding joins

From the course: Learning Data Analytics: 1 Foundations

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Understanding joins

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- [Instructor] One of the hardest concepts for new analysts is how to join data in multiple tables. There is no single best answer that is always applicable to every situation. If you're working with data sets that have already been joined for you, that is amazing. But when you're given the back-end access to multiple tables, you will likely need to join them, and you'll usually do this through queries. Another thing to keep in mind is that programs that work with multiple data sets typically provide you a way to join them. In Excel, it's VLOOKUPs. And in databases, it's queries. Each data set needs a way to relate the data, something shared on both sets of the data. In the best-case scenario, that is a key field that uniquely identifies the information, so you can use it to join. It's worth noting that in queries, there are different types of joins, like inner, outer, and cross joins. The type of join will determine the end result, so it's important to understand them. The more…

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