Beginning SQL Queries: From Novice to Professional, Second Edition

© Clare Churcher 2016

Clare Churcher, Beginning SQL Queries, 10.1007/978-1-4842-1955-3_3

3. A First Look at Joins

Clare Churcher¹ 

(1)Studio B Productions, Great Neck, New York, USA

In the previous chapter, we looked at how to retrieve subsets of rows and/or columns from a single table. We saw in Chapter 1 that to keep data accurately in a database, different aspects of the information need to be separated into normalized tables. Most queries will require information from two or more tables. We can combine data from two tables in several different ways depending on the nature of the information we are trying to extract. The most often encountered two-table operation is the join. In Chapter 1 we also introduced two different ways to approach a query: ...