What Is a JOIN?
In Chapter 2, Ensuring Your Database Structure Is Sound, we emphasized the importance of separating the data in your tables into individual subjects. Most problems you need to solve in real life, however, require that you link data from multiple tables—customers and their orders, customers and the entertainers they booked, bowlers and their scores, students and the classes they took, or recipes and the ingredients you need. To solve these more complex problems, you must link, or join, multiple tables to find your answer. You use the JOIN keyword to do so.
The previous chapter showed how useful it is to intersect two sets of data to solve problems. As you recall, however, an INTERSECT involves matching all the columns in both ...
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