DataReader cursor rewind

Question

How do I can rewind a cursor of a DataReader to the beginning?

With one DataReader result I need to run two while loop, but those have to be from beginn

Answer 1

You cannot (unless you execute the command again): it is a one-way stream. If you want to see the data more than once you'll have to buffer it in memory yourself, for example in a List<T> (for some T), or (yeuch) as a DataTable.