This is a common question and often answered incorrectly.
The DataReader returns the low-level data stream from the .NET data
provider. It is decoded by ADO.NET on a column-by-column basis using the
DataReader "Get" methods.
The DataAdapter Fill method uses a DataReader to construct an in-memory
DataSet, DataTable(s) and DataRows(s). NO, these are not stored as XML (that
would be very inefficient). The data is stored in linked arrays--one for
each column based on the datatype of the rowset column. If the application
wishes to extract or read the data in XML format, ADO.NET does so on the fly
as needed.
hth
--
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Bill Vaughn
MVP, hRD
www.betav.com
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