This class has a very important role in
select_result class and
classes inherited from it (usually called with a
select_ prefix). This class provides the
interface for transmitting results.
The key methods in this class are the following:
send_fields sends given item list headers
(type, name, etc.).
send_data sends given item list values as
row of table of result.
send_error is used mainly for error
interception, making some operation and then
::send_error will be called.
For example, there are the following
select_send used for sending results though
select_export used for exporting data to
multi_delete used for multi-delete.
select_insert used for
multi_update used for multi-update.
select_singlerow_subselect used for row and
select_exists_subselect used for
select_max_min_finder_subselect used for