TAILIEUCHUNG - Introduction 2

Introduction The DataSet is a disconnected, in-memory relational database that provides sophisticated navigational capabilities. It acts as a container for other objects including DataTable, DataColumn, DataRow, and DataRelation. | Team LiB Introduction The DataSet is a disconnected in-memory relational database that provides sophisticated navigational capabilities. It acts as a container for other objects including DataTable DataColumn DataRow and DataRelation. The DataAdapter works with the DataSet to update the data source with changes made offline to the DataSet. You can also data bind a DataSet to a variety of Windows Forms and Web Forms controls in particular any control that supports the IList interface. The DataSet maintains both current and original versions of its data. Although data appears to be changed it is not permanently changed until the AcceptChanges method is called either explicitly or implicitly to commit the changes. Recipe shows how to access rows marked for deletion. The DataReader provides forward-only read-only access to a result set. The DataReader offers the best performance for accessing data by avoiding the overhead associated with the DataSet. The Connection object underlying a DataReader remains open and cannot be used for any other purpose while data is being accessed. This makes the DataReader unsuitable for communicating data remotely between application tiers or interacting with the data dynamically. If you want to discard a result set in a DataReader before the entire result set has been read call the Cancel method of the DataReader before calling the Close method. This discards the results on the server so they are not transmitted to the client. Simply calling Close causes the remaining results to be pulled to the client to empty the stream. Since the DataReader reads a result set stream directly from a connection there is no way to know the number of records in a DataReader. Recipe demonstrates techniques that simulate a record count for a DataReader and discusses limitations of the techniques. You can define DataSet and DataReader object schemas programmatically or infer them from a database schema. Retrieving schema information from the .

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