SQL Queries for Mere Mortals: A Hands-On Guide to Data Manipulation in SQL, Second Edition

Summary

In this chapter, we led you through the world of OUTER JOINs. We began by defining an OUTER JOIN and comparing it to the INNER JOIN you learned about in Chapter 8.

We next explained how to construct a LEFT or RIGHT OUTER JOIN, beginning with simple examples using two tables, and then progressing to embedding SELECT statements and constructing statements using multiple JOINs. We showed how an OUTER JOIN combined with a Null test is equivalent to the difference (EXCEPT) operation we covered in Chapter 7. We also discussed some of the difficulties you might encounter when constructing statements using multiple OUTER JOINs. We closed the discussion of the LEFT and RIGHT OUTER JOIN with a problem requiring multiple OUTER JOINs that can’t ...