Extending MFC Applications with the .NET Framework

Associating Related Tables with the DataRelation Class

One of the most powerful aspects of ADO.NET—and, specifically, of the DataSet class—is the ability to define relationships between related tables such that both tables can be navigated more easily and efficiently. For example, let's say you have a typical order entry system with both an OrderHeaders and OrderDetails table. In fact, the sample database (ExtendingMFCWithDotNet) provided on the CD with this book contains two such tables whose schemas are shown in Tables 7-2 and 7-3.

Table 7-2. Sample OrderHeaders Table Schema

Primary Key (y/n)	IDENTITY (y/n)	Column Name	Type
YES	YES	OrderId	int
		CompanyName	varchar
		ShippingAddress	varchar

Table 7-3. Sample OrderDetails Table Schema

Primary Key (y/n)