def select_row(statement, build_arg = nil)
    rows = select(statement, build_arg)
    raise UnexpectedQueryResult, "selected #{rows.size} rows; expected 1" unless rows.size == 1
    rows[0]
  end
def select_row(statement, build_arg = nil)
    rows = select(statement, build_arg)
    raise UnexpectedQueryResult, "selected #{rows.size} rows; expected 1" unless rows.size == 1
    rows[0]
  end
Simple convenience wrapper around the generic select call.
 Throws an exception unless the result set is a single row.
 Returns the row selected.