O'Reilly logo

Tera-Tom on Teradata SQL V12-V13 by Tera-Tom Coffing

Stay ahead with the world's most comprehensive technology and business learning platform.

With Safari, you learn the way you learn best. Get unlimited access to videos, live online training, learning paths, books, tutorials, and more.

Start Free Trial

No credit card required

Chapter 7 – Join Processing

Join Processing

A join is the combination of two or more tables in the same FROM of a single SELECT statement. When writing a join, the key is to locate a column in both tables that is from a common domain. Like the correlated subquery, joins are normally based on an equal comparison between the join columns.

An example of a common domain column might be a customer number. Whether it represents a particular customer, as the primary key, in the Customer table, or the customer that placed a specific order, as a foreign key, in the Order table, it represents the same entity in both tables. Without a common value, a match cannot be made and therefore, no rows can be selected using a join. An Equality join returns ...

With Safari, you learn the way you learn best. Get unlimited access to videos, live online training, learning paths, books, interactive tutorials, and more.

Start Free Trial

No credit card required