Database Relationships and Constraints
Before discussing how to create data relations inside a DataSet, it makes sense to explain how relationships function inside a relational database system such as Microsoft SQL Server. If you are already familiar with relational databases, you might want to skip ahead to the section entitled “The DataRelation Object.”
Suppose you have to store information about customer orders inside a database. You might choose to use a database schema like the one shown in the database diagram in Figure 4.1. There are five tables in this diagram, and they are all related to the main Orders table. Notice the lines connecting the tables together. Each of these lines represents a relationship in the database. ...