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_fieldssends given item list headers (type, name, etc.).
send_datasends given item list values as row of table of result.
send_erroris used mainly for error interception, making some operation and then
::send_errorwill be called.
For example, there are the following
select_sendused for sending results though network layer.
select_exportused for exporting data to file.
multi_deleteused for multi-delete.
multi_updateused for multi-update.
select_singlerow_subselectused for row and scalar subqueries..
select_max_min_finder_subselectused for min/max subqueries (