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In ADO.NET, a DataReader is a broad category of objects used to sequentially read data from a data source. DataReaders provide a very efficient way to access data, and can be thought of as a Firehose cursor from ASP Classic, except that no server-side cursor is used. A DataReader parses a Tabular Data Stream from Microsoft SQL Server, and other methods of retrieving data from other sources. A DataReader is usually accompanied by a Command object that contains the query, optionally any parameters, and the connection object to run the query on. ==DataReader Types== There is no DataReader class in ADO.NET, but there are a number of classes that implement the IDataReader interface: * System.Data.SqlClient.SqlDataReader * System.Data.OleDb.OleDbDataReader * Oracle.OracleClient.OracleDataReader DataReaders have a small footprint and good performance because each is tailor-made to the task at hand, however this makes it more difficult to write an application that can be moved from one backend data source to another. Some provider-specific DataReaders expose types used by the underlying database - for example, int values can be null in Microsoft SQL Server, but not in the .NET Framework prior to version 2.0. 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「DataReader」の詳細全文を読む スポンサード リンク
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