string strMultiSelect = "Select * from Categories; Select * from Product";
 // conn is OledbConnection
    OledbCommand      cmdMultiSelect = new OledbCommand(strMultiSelect,conn)
   DataReader drMultiReader = cmdMultiSelect.ExecuteReader()
  do
{
 while(drMultiReader.Read())
{
 // access all the fileds for the first select command
   System.Consol.Write(drMultiReader[0]);
}

}
// moving to the next select command or result set in the DataReader
while(drMultiReader.NextResult());