Item_ref Class Reference

Inheritance diagram for Item_ref:

Collaboration diagram for Item_ref:

Public Types
enum	Ref_Type {   REF, DIRECT_REF, VIEW_REF, OUTER_REF,   AGGREGATE_REF }

Public Member Functions
	Item_ref (Name_resolution_context *context_arg, const char *db_arg, const char *table_name_arg, const char *field_name_arg)
	Item_ref (Name_resolution_context *context_arg, Item **item, const char *table_name_arg, const char *field_name_arg, bool alias_name_used_arg=FALSE)
	Item_ref (THD *thd, Item_ref *item)
enum Type	type () const
bool	eq (const Item *item, bool binary_cmp) const
double	val_real ()
longlong	val_int ()
longlong	val_time_temporal ()
longlong	val_date_temporal ()
my_decimal *	val_decimal (my_decimal *)
bool	val_bool ()
String *	val_str (String *tmp)
bool	is_null ()
bool	get_date (MYSQL_TIME *ltime, uint fuzzydate)
double	val_result ()
longlong	val_int_result ()
String *	str_result (String *tmp)
my_decimal *	val_decimal_result (my_decimal *)
bool	val_bool_result ()
bool	is_null_result ()
bool	send (Protocol *prot, String *tmp)
void	make_field (Send_field *field)
bool	fix_fields (THD *, Item **)
void	fix_after_pullout (st_select_lex *parent_select, st_select_lex *removed_select)
type_conversion_status	save_in_field (Field *field, bool no_conversions)
void	save_org_in_field (Field *field)
enum Item_result	result_type () const
enum_field_types	field_type () const
Field *	get_tmp_table_field ()
Item *	get_tmp_table_item (THD *thd)
bool	const_item () const
table_map	used_tables () const
void	update_used_tables ()
virtual table_map	resolved_used_tables () const
table_map	not_null_tables () const
void	set_result_field (Field *field)
bool	is_result_field ()
void	save_in_result_field (bool no_conversions)
Item *	real_item ()
bool	walk (Item_processor processor, bool walk_subquery, uchar *arg)
virtual Item *	transform (Item_transformer, uchar *arg)
virtual Item *	compile (Item_analyzer analyzer, uchar **arg_p, Item_transformer transformer, uchar *arg_t)
virtual bool	explain_subquery_checker (uchar **arg)
virtual void	print (String *str, enum_query_type query_type)
void	cleanup ()
Item_field *	field_for_view_update ()
virtual Ref_Type	ref_type ()
uint	cols ()
Item *	element_index (uint i)
Item **	addr (uint i)
bool	check_cols (uint c)
bool	null_inside ()
void	bring_value ()
bool	get_time (MYSQL_TIME *ltime)
virtual bool	basic_const_item () const
bool	is_outer_field () const
virtual bool	has_subquery () const
virtual bool	has_stored_program () const
virtual bool	created_by_in2exists () const
	Whether this Item was created by the IN->EXISTS subquery transformation.
Public Member Functions inherited from Item_ident
	Item_ident (Name_resolution_context *context_arg, const char *db_name_arg, const char *table_name_arg, const char *field_name_arg)
	Item_ident (THD *thd, Item_ident *item)
const char *	full_name () const
bool	remove_dependence_processor (uchar *arg)
virtual bool	change_context_processor (uchar *cntx)
Public Member Functions inherited from Item
	Item (THD *thd, Item *item)
void	rename (char *new_name)
void	init_make_field (Send_field *tmp_field, enum enum_field_types type)
virtual Field *	make_string_field (TABLE *table)
void	quick_fix_field ()
type_conversion_status	save_in_field_no_warnings (Field *field, bool no_conversions)
virtual type_conversion_status	save_safe_in_field (Field *field)
virtual enum Item_result	numeric_context_result_type () const
enum Item_result	temporal_with_date_as_number_result_type () const
virtual Item_result	cast_to_int_type () const
virtual enum_field_types	string_field_type () const
virtual enum_monotonicity_info	get_monotonicity_info () const
virtual longlong	val_int_endpoint (bool left_endp, bool *incl_endp)
longlong	val_temporal_by_field_type ()
longlong	val_temporal_with_round (enum_field_types type, uint8 dec)
ulonglong	val_uint ()
virtual String *	val_str_ascii (String *str)
virtual String *	val_nodeset (String *)
type_conversion_status	save_time_in_field (Field *field)
type_conversion_status	save_date_in_field (Field *field)
type_conversion_status	save_str_value_in_field (Field *field, String *result)
virtual Field *	tmp_table_field (TABLE *t_arg)
virtual longlong	val_time_temporal_result ()
virtual longlong	val_date_temporal_result ()
virtual Item *	clone_item ()
virtual cond_result	eq_cmp_result () const
uint	float_length (uint decimals_par) const
virtual uint	decimal_precision () const
int	decimal_int_part () const
virtual uint	time_precision ()
virtual uint	datetime_precision ()
virtual bool	const_during_execution () const
void	print_item_w_name (String *, enum_query_type query_type)
void	print_for_order (String *str, enum_query_type query_type, bool used_alias)
virtual void	split_sum_func (THD *thd, Ref_ptr_array ref_pointer_array, List< Item > &fields)
void	split_sum_func2 (THD *thd, Ref_ptr_array ref_pointer_array, List< Item > &fields, Item **ref, bool skip_registered)
virtual bool	get_timeval (struct timeval *tm, int *warnings)
virtual bool	get_date_result (MYSQL_TIME *ltime, uint fuzzydate)
virtual void	update_null_value ()
virtual void	top_level_item ()
virtual bool	is_bool_func ()
virtual void	no_rows_in_result ()
virtual Item *	copy_or_same (THD *thd)
virtual Item *	copy_andor_structure (THD *thd, bool real_items=false)
virtual const CHARSET_INFO *	compare_collation ()
virtual const CHARSET_INFO *	charset_for_protocol (void) const
virtual void	traverse_cond (Cond_traverser traverser, void *arg, traverse_order order)
virtual bool	intro_version (uchar *int_arg)
virtual bool	remove_fixed (uchar *arg)
virtual bool	cleanup_processor (uchar *arg)
virtual bool	collect_item_field_processor (uchar *arg)
virtual bool	add_field_to_set_processor (uchar *arg)
virtual bool	remove_column_from_bitmap (uchar *arg)
virtual bool	find_item_in_field_list_processor (uchar *arg)
virtual bool	reset_query_id_processor (uchar *query_id_arg)
virtual bool	find_item_processor (uchar *arg)
virtual bool	register_field_in_read_map (uchar *arg)
virtual bool	inform_item_in_cond_of_tab (uchar *join_tab_index)
virtual bool	clean_up_after_removal (uchar *arg)
virtual bool	cache_const_expr_analyzer (uchar **arg)
virtual Item *	cache_const_expr_transformer (uchar *arg)
virtual bool	item_field_by_name_analyzer (uchar **arg)
virtual Item *	item_field_by_name_transformer (uchar *arg)
virtual bool	equality_substitution_analyzer (uchar **arg)
virtual Item *	equality_substitution_transformer (uchar *arg)
virtual bool	check_partition_func_processor (uchar *bool_arg)
virtual bool	subst_argument_checker (uchar **arg)
virtual Item *	explain_subquery_propagator (uchar *arg)
virtual Item *	equal_fields_propagator (uchar *arg)
virtual bool	set_no_const_sub (uchar *arg)
virtual Item *	replace_equal_field (uchar *arg)
virtual bool	check_valid_arguments_processor (uchar *bool_arg)
virtual bool	find_function_processor (uchar *arg)
virtual Item *	this_item ()
virtual const Item *	this_item () const
virtual Item **	this_item_addr (THD *thd, Item **addr_arg)
Field *	tmp_table_field_from_field_type (TABLE *table, bool fixed_length)
virtual Item *	neg_transformer (THD *thd)
virtual Item *	update_value_transformer (uchar *select_arg)
virtual Item *	safe_charset_converter (const CHARSET_INFO *tocs)
void	delete_self ()
virtual bool	is_splocal ()
virtual Settable_routine_parameter *	get_settable_routine_parameter ()
bool	is_temporal_with_date () const
bool	is_temporal_with_date_and_time () const
bool	is_temporal_with_time () const
bool	is_temporal () const
bool	has_compatible_context (Item *item) const
virtual Field::geometry_type	get_geometry_type () const
String *	check_well_formed_result (String *str, bool send_error=0)
bool	eq_by_collation (Item *item, bool binary_cmp, const CHARSET_INFO *cs)
virtual bool	is_expensive ()
virtual bool	can_be_evaluated_now () const
uint32	max_char_length () const
void	fix_length_and_charset (uint32 max_char_length_arg, const CHARSET_INFO *cs)
void	fix_char_length (uint32 max_char_length_arg)
void	fix_char_length_ulonglong (ulonglong max_char_length_arg)
void	fix_length_and_charset_datetime (uint32 max_char_length_arg)
void	fix_length_and_dec_and_charset_datetime (uint32 max_char_length_arg, uint8 dec_arg)
bool	is_blob_field () const

Public Attributes
Field *	result_field
Item **	ref
Public Attributes inherited from Item_ident
Name_resolution_context *	context
const char *	db_name
const char *	table_name
const char *	field_name
bool	alias_name_used
uint	cached_field_index
TABLE_LIST *	cached_table
st_select_lex *	depended_from
Public Attributes inherited from Item
uint	rsize
String	str_value
Item_name_string	item_name
Item_name_string	orig_name
Item *	next
uint32	max_length
int	marker
uint8	decimals
my_bool	maybe_null
my_bool	null_value
my_bool	unsigned_flag
my_bool	with_sum_func
my_bool	fixed
DTCollation	collation
Item_result	cmp_context

Protected Member Functions
void	set_properties ()

Additional Inherited Members
Static Public Member Functions inherited from Item
static void *	operator new (size_t size) throw ()
static void *	operator new (size_t size, MEM_ROOT *mem_root) throw ()
static void	operator delete (void *ptr, size_t size)
static void	operator delete (void *ptr, MEM_ROOT *mem_root)
static const CHARSET_INFO *	default_charset ()
Protected Attributes inherited from Item_ident
const char *	orig_db_name
const char *	orig_table_name
const char *	orig_field_name

Detailed Description

Definition at line 3128 of file item.h.

Member Function Documentation

Item * Item_ref::compile ( Item_analyzer  analyzer, uchar **  arg_p, Item_transformer  transformer, uchar *  arg_t  )

virtual

Compile an Item_ref object with a processor and a transformer callback function.

First the function applies the analyzer to the Item_ref object. Second it applies the compile function to the object the Item_ref object is referencing. If this replaces the item with a new one, this object is returned as the result of the compile. Otherwise we apply the transformer to the Item_ref object itself.

Parameters

	analyzer	the analyzer callback function to be applied to the nodes of the tree of the object
[in,out]	arg_p	parameter to be passed to the processor
	transformer	the transformer callback function to be applied to the nodes of the tree of the object
	arg_t	parameter to be passed to the transformer

Returns

Item returned as the result of transformation of the Item_ref object, or NULL if error.

Reimplemented from Item.

Definition at line 7476 of file item.cc.

bool Item_ref::eq ( const Item *  item, bool  binary_cmp  ) const

inlinevirtual

This function is called when:

• Comparing items in the WHERE clause (when doing where optimization)
• When trying to find an ORDER BY/GROUP BY item in the SELECT part
• When matching fields in multiple equality objects (Item_equal)

Reimplemented from Item.

Reimplemented in Item_direct_view_ref.

Definition at line 3163 of file item.h.

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void Item_ref::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_ident.

Reimplemented in Item_outer_ref.

Definition at line 7912 of file item.cc.

bool Item_ref::fix_fields ( THD *  thd, Item **  reference  )

virtual

Resolve the name of a reference to a column reference.

The method resolves the column reference represented by 'this' as a column present in one of: GROUP BY clause, SELECT clause, outer queries. It is used typically for columns in the HAVING clause which are not under aggregate functions.

POSTCONDITION
Item_ref::ref is 0 or points to a valid item.

Note

The name resolution algorithm used is (where [T_j] is an optional table name that qualifies the column name):

resolve_extended([T_j].col_ref_i)
{
  Search for a column or derived column named col_ref_i [in table T_j]
  in the SELECT and GROUP clauses of Q.

  if such a column is NOT found AND    // Lookup in outer queries.
     there are outer queries
  {
    for each outer query Q_k beginning from the inner-most one
   {
      Search for a column or derived column named col_ref_i
      [in table T_j] in the SELECT and GROUP clauses of Q_k.

      if such a column is not found AND
         - Q_k is not a group query AND
         - Q_k is not inside an aggregate function
         OR
         - Q_(k-1) is not in a HAVING or SELECT clause of Q_k
      {
        search for a column or derived column named col_ref_i
        [in table T_j] in the FROM clause of Q_k;
      }
    }
  }
}

This procedure treats GROUP BY and SELECT clauses as one namespace for column references in HAVING. Notice that compared to Item_field::fix_fields, here we first search the SELECT and GROUP BY clauses, and then we search the FROM clause.

Parameters

[in]	thd	current thread
[in,out]	reference	view column if this item was resolved to a view column

Todo:

Here we could first find the field anyway, and then test this condition, so that we can give a better error message - ER_WRONG_FIELD_WITH_GROUP, instead of the less informative ER_BAD_FIELD_ERROR which we produce now.

Return values

TRUE	if error
FALSE	on success

Reimplemented from Item.

Reimplemented in Item_outer_ref, and Item_direct_view_ref.

Definition at line 7147 of file item.cc.

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virtual bool Item_ref::has_stored_program ( ) const

inlinevirtual

Checks if the item tree that ref points to contains a stored program.

Reimplemented from Item.

Definition at line 3308 of file item.h.

virtual bool Item_ref::has_subquery ( ) const

inlinevirtual

Checks if the item tree that ref points to contains a subquery.

Reimplemented from Item.

Definition at line 3299 of file item.h.

void Item_ref::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_ident.

Reimplemented in Item_ref_null_helper, and Item_aggregate_ref.

Definition at line 7498 of file item.cc.

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virtual table_map Item_ref::resolved_used_tables ( ) const

inlinevirtual

Return used table information for the level this item is resolved on.

• For fields, this returns the table the item is resolved from.
• For all other items, this behaves like used_tables().

Note

: Use this function with caution. External calls to this function should only be made for class objects derived from Item_ident. Item::resolved_used_tables is for internal use only, in order to process fields underlying a view column reference.

Reimplemented from Item.

Definition at line 3209 of file item.h.

type_conversion_status Item_ref::save_in_field ( Field *  field, bool  no_conversions  )

virtual

Save a temporal value in packed longlong format into a Field. Used in optimizer.

Parameters

OUT	field The field to set the value to.

Return values

0	On success.
>0	In error.

Reimplemented from Item.

Definition at line 7690 of file item.cc.

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bool Item_ref::send ( Protocol *  protocol, String *  buffer  )

virtual

This is only called from items that is not of type item_field.

Reimplemented from Item.

Definition at line 7516 of file item.cc.

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Item * Item_ref::transform ( Item_transformer  transformer, uchar *  arg  )

virtual

Transform an Item_ref object with a transformer callback function.

The function first applies the transform function to the item referenced by this Item_ref object. If this replaces the item with a new one, this item object is returned as the result of the transform. Otherwise the transform function is applied to the Item_ref object itself.

Parameters

transformer	the transformer callback function to be applied to the nodes of the tree of the object
argument	parameter to be passed to the transformer

Returns

Item returned as the result of transformation of the Item_ref object

Return values

!NULL	The transformation was successful
NULL	Out of memory error

Reimplemented from Item.

Definition at line 7431 of file item.cc.

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bool Item_ref::val_bool ( )

virtual

Todo:

Make this functions class dependent

Reimplemented from Item.

Reimplemented in Item_ref_null_helper, and Item_direct_ref.

Definition at line 7649 of file item.cc.

longlong Item_ref::val_date_temporal ( )

virtual

Return date value of item in packed longlong format.

Reimplemented from Item.

Reimplemented in Item_ref_null_helper, and Item_direct_ref.

Definition at line 7639 of file item.cc.

longlong Item_ref::val_time_temporal ( )

virtual

Return time value of item in packed longlong format.

Reimplemented from Item.

Reimplemented in Item_ref_null_helper, and Item_direct_ref.

Definition at line 7629 of file item.cc.

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

• sql/item.h
• sql/item.cc