The DataReader object
represents a read-only, forward-only stream of data, which is ideal
for quickly retrieving query results. The
DataReader is useful if you don't
need the full support for versioning and change tracking provided by
the DataSet. Best of all, because the
DataReader loads only a single row into memory at
a time, it has a small in-memory footprint.
You can't create a DataReader
directly. Instead, you must use the ExecuteReader(
method of a Command object that returns a
DataReader. Chapter 5 presents
complete examples that show how to use the
DataReader in various scenarios.