SQL Tutorial: Tables: At the core of every database

Want to learn more? Take the full course at https://learn.datacamp.com/courses/introduction-to-relational-databases-in-sql at your own pace. More than a video, you'll learn hands-on coding & quickly apply skills to your daily work. --- Now that you've had a first look at your database, let's delve into one of the most important concepts behind databases: tables. You might have noticed that there's some redundancy in the "university_professors" table. Let's have a look at the first three records, for example. As you can see, this professor is repeated in the first three records. Also, his university, the "ETH Lausanne", is repeated a couple of times – because he only works for this university. However, he seems to have affiliations with at least three different organizations. So, there's a certain redundancy in that table. The reason for this is that the table actually contains entities of at least three different types. Let's have a look at these entity types. Actually the table stores professors, highlighted in blue, universities, highlighted in green, and organizations, highlighted in brown. There's also this column called "function" which denotes the role the professor plays at a certain organization. More on that later. Let's look at the current database once again. The graphic used here is called an entity-relationship diagram. Squares denote so-called entity types, while circles connected to these denote attributes (or columns). So far, we have only modeled one so-called entity type – "university_professors". However, we discovered that this table actually holds many different entity types... ...so this updated entity-relationship model on the right side would be better suited. It represents three entity types, "professors", "universities", and "organizations" in their own tables, with respective attributes. This reduces redundancy, as professors, unlike now, need to be stored only once. Note that, for each professor, the respective university is also d