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JOINS - Multiple tables

Joining more than 2 tables

Let’s say the task is to display the name and publisherName of all books which have an author and a course they belong to, with the name of the course, and the name of their author.

In this case, we will need to JOIN the table books with courses and authors in the same query. The query would look something like this

Observe that the only differences in this query from a standard JOIN query are:

  1. An extra table name in the FROM list, separated by JOIN

  2. An additional condition in the ON clause, joined by AND

This simply means that we include all the tables that we need to pick up data from in the FROM list, and then mention all the relationships between columns that need to matched across the tables for the JOIN to work correctly, in the ON clause.