As mentioned, the DataSet object is the cornerstone of ADO.NET development. The DataSet contains a set of DataTables, as well as any relationships between those tables. Figure 2.1 shows the relationships between the objects within the DataSet.
In a relational database, a relationship is a link between two entities (such as tables) that is based on attributes of the entities. For instance, if you have a table of customer information, you might link their CustomerID to the CustomerInvoice table, so that only valid customers in the database are invoiced. ...