The Language of SQL, Second Edition

11. Inner Joins

Keywords Introduced

INNER JOIN  •  ON

Back in Chapter 1, we talked about the huge advance of relational databases over their predecessors. The significant achievement of relational databases was in their ability to allow data to be organized in any number of tables that are related but at the same time independent of each other. Prior to the advent of relational databases, traditional databases utilized a chain of internal pointers to explicitly define the relationships between tables. For example, you might start with a Customers table and then follow pointers to find the first order for a particular customer, then the next order, and so on until all orders for the customer have been retrieved. In contrast, relational databases ...