.NET Windows Forms in a Nutshell

DataTable, DataSet, and Friends

Although the data-binding architecture is flexible enough to bind to any property of any object, the .NET Framework provides a group of classes (part of ADO.NET) that have much more extensive data-binding support. At the center of this family are the DataSet and DataTable classes in the System.Data namespace. These form the basis for the disconnected use of data from a database, and they are designed to allow flexible presentation of data while making efficient use of server resources.

All presentation of data from a database in Windows Forms is based around a disconnected model—clients connect to a database and retrieve all the data they require in a single step. They do not hold onto any server-side resources (such as cursors) after this data has been retrieved, and can therefore release their connection to the database. (In practice, the connection will normally be returned to a pool rather than being freed completely.) This is a departure from previous data-binding models, where disconnected operation was strictly optional. This new model reduces the workload on the server, because at any given instant it has to deal with fewer clients, thus improving the scalability of the system.

The DataTable class allows a snapshot of part (or all) of a database table to be held on the client. The DataSet class can hold any number of DataTable objects, and can also contain information about relations between these tables. (Relations are represented as