Item_row Class Reference

Inheritance diagram for Item_row:

List of all members.

Public Member Functions
	Item_row (List< Item > &)
	Item_row (Item *head, List< Item > &tail)
	Item_row (Item_row *item)
enum Type	type () const
void	illegal_method_call (const char *)
bool	is_null ()
void	make_field (Send_field *)
double	val_real ()
longlong	val_int ()
String *	val_str (String *)
my_decimal *	val_decimal (my_decimal *)
bool	get_date (MYSQL_TIME *ltime, uint fuzzydate)
bool	get_time (MYSQL_TIME *ltime)
bool	fix_fields (THD *thd, Item **ref)
void	fix_after_pullout (st_select_lex *parent_select, st_select_lex *removed_select)
void	cleanup ()
void	split_sum_func (THD *thd, Ref_ptr_array ref_pointer_array, List< Item > &fields)
table_map	used_tables () const
bool	const_item () const
enum Item_result	result_type () const
void	update_used_tables ()
table_map	not_null_tables () const
virtual void	print (String *str, enum_query_type query_type)
bool	walk (Item_processor processor, bool walk_subquery, uchar *arg)
Item *	transform (Item_transformer transformer, uchar *arg)
uint	cols ()
Item *	element_index (uint i)
Item **	addr (uint i)
bool	check_cols (uint c)
bool	null_inside ()
void	bring_value ()

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Constructor & Destructor Documentation

Item_row::Item_row

(

List< Item > &

arg

)

Row items used for comparing rows and IN operations on rows:

  (a, b, c) > (10, 10, 30)
  (a, b, c) = (select c, d, e, from t1 where x=12)
  (a, b, c) IN ((1,2,2), (3,4,5), (6,7,8)
  (a, b, c) IN (select c, d, e, from t1)
  

Todo:

think placing 2-3 component items in item (as it done for function

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Member Function Documentation

void Item_row::fix_after_pullout	(	st_select_lex *	parent_select,
		st_select_lex *	removed_select
	)		[virtual]

Fix after tables have been moved from one select_lex level to the parent level, e.g by semijoin conversion. Basically re-calculate all attributes dependent on the tables.

Parameters:

parent_select	select_lex that tables are moved to.
removed_select	select_lex that tables are moved away from, child of parent_select.

Reimplemented from Item.

void Item_row::print	(	String *	str,
		enum_query_type	query_type
	)		[virtual]

This method is used for to:

• to generate a view definition query (SELECT-statement);
• to generate a SQL-query for EXPLAIN EXTENDED;
• to generate a SQL-query to be shown in INFORMATION_SCHEMA;
• debug.

For more information about view definition query, INFORMATION_SCHEMA query and why they should be generated from the Item-tree,

See also:

mysql_register_view().

Reimplemented from Item.

Item * Item_row::transform	(	Item_transformer	transformer,
		uchar *	arg
	)		[virtual]

Traverse item tree possibly transforming it (replacing items).

This function is designed to ease transformation of Item trees. Re-execution note: every such transformation is registered for rollback by THD::change_item_tree() and is rolled back at the end of execution by THD::rollback_item_tree_changes().

Therefore:

• this function can not be used at prepared statement prepare (in particular, in fix_fields!), as only permanent transformation of Item trees are allowed at prepare.
• the transformer function shall allocate new Items in execution memory root (thd->mem_root) and not anywhere else: allocated items will be gone in the end of execution.

If you don't need to transform an item tree, but only traverse it, please use Item::walk() instead.

Parameters:

transformer	functor that performs transformation of a subtree
arg	opaque argument passed to the functor

Returns:

Returns pointer to the new subtree root. THD::change_item_tree() should be called for it if transformation took place, i.e. if a pointer to newly allocated item is returned.

Reimplemented from Item.

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The documentation for this class was generated from the following files:

• item_row.h
• item_row.cc