Inheritance diagram for Item_field:

Collaboration diagram for Item_field:

Public Member Functions
	Item_field (Name_resolution_context context_arg, const char db_arg, const char table_name_arg, const char field_name_arg)
	Item_field (THD thd, Item_field item)
	Item_field (THD thd, Name_resolution_context context_arg, Field *field)
	Item_field (Field *field)
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 *)
String *	val_str (String *)
double	val_result ()
longlong	val_int_result ()
longlong	val_time_temporal_result ()
longlong	val_date_temporal_result ()
String *	str_result (String *tmp)
my_decimal *	val_decimal_result (my_decimal *)
bool	val_bool_result ()
bool	is_null_result ()
bool	send (Protocol protocol, String str_arg)
void	reset_field (Field *f)
bool	fix_fields (THD , Item *)
void	make_field (Send_field *tmp_field)
type_conversion_status	save_in_field (Field *field, bool no_conversions)
void	save_org_in_field (Field *field)
table_map	used_tables () const
virtual table_map	resolved_used_tables () const
enum Item_result	result_type () const
enum Item_result	numeric_context_result_type () const
Item_result	cast_to_int_type () const
enum_field_types	field_type () const
enum_monotonicity_info	get_monotonicity_info () const
longlong	val_int_endpoint (bool left_endp, bool *incl_endp)
Field *	get_tmp_table_field ()
Field *	tmp_table_field (TABLE *t_arg)
bool	get_date (MYSQL_TIME *ltime, uint fuzzydate)
bool	get_date_result (MYSQL_TIME *ltime, uint fuzzydate)
bool	get_time (MYSQL_TIME *ltime)
bool	get_timeval (struct timeval tm, int warnings)
bool	is_null ()
void	update_null_value ()
Item *	get_tmp_table_item (THD *thd)
bool	collect_item_field_processor (uchar *arg)
bool	add_field_to_set_processor (uchar *arg)
bool	remove_column_from_bitmap (uchar *arg)
bool	find_item_in_field_list_processor (uchar *arg)
bool	register_field_in_read_map (uchar *arg)
bool	check_partition_func_processor (uchar *int_arg)
void	cleanup ()
Item_equal *	find_item_equal (COND_EQUAL *cond_equal)
bool	subst_argument_checker (uchar **arg)
Item *	equal_fields_propagator (uchar *arg)
bool	set_no_const_sub (uchar *arg)
Item *	replace_equal_field (uchar *arg)
uint32	max_disp_length ()
Item_field *	field_for_view_update ()
Item *	safe_charset_converter (const CHARSET_INFO *tocs)
int	fix_outer_field (THD thd, Field field, Item *reference)
virtual Item *	update_value_transformer (uchar *select_arg)
virtual bool	item_field_by_name_analyzer (uchar **arg)
virtual Item *	item_field_by_name_transformer (uchar *arg)
virtual void	print (String *str, enum_query_type query_type)
bool	is_outer_field () const
Field::geometry_type	get_geometry_type () const
const CHARSET_INFO *	charset_for_protocol (void) const
void	dbug_print ()
bool	push_to_non_agg_fields (st_select_lex *select_lex)
	Pushes the item to select_lex.non_agg_fields() and updates its marker.
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
virtual void	fix_after_pullout (st_select_lex parent_select, st_select_lex removed_select)
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)
enum Item_result	temporal_with_date_as_number_result_type () const
virtual enum_field_types	string_field_type () const
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 bool	val_bool ()
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 table_map	not_null_tables () const
virtual bool	basic_const_item () const
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_item () const
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	update_used_tables ()
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 void	top_level_item ()
virtual void	set_result_field (Field *field)
virtual bool	is_result_field ()
virtual bool	is_bool_func ()
virtual void	save_in_result_field (bool no_conversions)
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 Item *	real_item ()
virtual const CHARSET_INFO *	compare_collation ()
virtual bool	walk (Item_processor processor, bool walk_subquery, uchar *arg)
virtual Item *	transform (Item_transformer transformer, uchar *arg)
virtual Item *	compile (Item_analyzer analyzer, uchar *arg_p, Item_transformer transformer, uchar arg_t)
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	reset_query_id_processor (uchar *query_id_arg)
virtual bool	find_item_processor (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	equality_substitution_analyzer (uchar **arg)
virtual Item *	equality_substitution_transformer (uchar *arg)
virtual bool	explain_subquery_checker (uchar **arg)
virtual Item *	explain_subquery_propagator (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)
virtual uint	cols ()
virtual Item *	element_index (uint i)
virtual Item **	addr (uint i)
virtual bool	check_cols (uint c)
virtual bool	null_inside ()
virtual void	bring_value ()
Field *	tmp_table_field_from_field_type (TABLE *table, bool fixed_length)
virtual Item *	neg_transformer (THD *thd)
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
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
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 Attributes
Field *	field
Field *	result_field
Item_equal *	item_equal
bool	no_const_subst
uint	have_privileges
bool	any_privileges
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_field (Field *field)

Friends
class	Item_default_value
class	Item_insert_value
class	st_select_lex_unit

Additional Inherited Members
Public Types inherited from Item
enum	Type { FIELD_ITEM = 0, FUNC_ITEM, SUM_FUNC_ITEM, STRING_ITEM, INT_ITEM, REAL_ITEM, NULL_ITEM, VARBIN_ITEM, COPY_STR_ITEM, FIELD_AVG_ITEM, DEFAULT_VALUE_ITEM, PROC_ITEM, COND_ITEM, REF_ITEM, FIELD_STD_ITEM, FIELD_VARIANCE_ITEM, INSERT_VALUE_ITEM, SUBSELECT_ITEM, ROW_ITEM, CACHE_ITEM, TYPE_HOLDER, PARAM_ITEM, TRIGGER_FIELD_ITEM, DECIMAL_ITEM, XPATH_NODESET, XPATH_NODESET_CMP, VIEW_FIXER_ITEM }
enum	cond_result { COND_UNDEF, COND_OK, COND_TRUE, COND_FALSE }
enum	traverse_order { POSTFIX, PREFIX }
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 2151 of file item.h.

Constructor & Destructor Documentation

Item_field::Item_field	(	THD *	thd,
		Item_field *	item
	)

Constructor need to process subselect with temporary tables (see Item)

Definition at line 2472 of file item.cc.

Item_field::Item_field	(	THD *	thd,
		Name_resolution_context *	context_arg,
		Field *	f
	)

Constructor used inside setup_wild().

Ensures that field, table, and database names will live as long as Item_field (this is important in prepared statements).

Definition at line 2414 of file item.cc.

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Member Function Documentation

bool Item_field::collect_item_field_processor ( uchar * arg )

virtual

Store the pointer to this item field into a list if not already there.

The method is used by Item::walk to collect all unique Item_field objects from a tree of Items into a set of items represented as a list.

Item_cond::walk() and Item_func::walk() stop the evaluation of the processor function for its arguments once the processor returns true.Therefore in order to force this method being called for all item arguments in a condition the method must return false.

Parameters

arg	pointer to a List<Item_field>

Returns: FALSE to force the evaluation of collect_item_field_processor for the subsequent items.

Reimplemented from Item.

Definition at line 873 of file item.cc.

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

virtual

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_insert_value, and Item_default_value.

Definition at line 2829 of file item.cc.

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Item * Item_field::equal_fields_propagator ( uchar * arg )

virtual

Set a pointer to the multiple equality the field reference belongs to (if any).

The function looks for a multiple equality containing the field item among those referenced by arg. In the case such equality exists the function does the following. If the found multiple equality contains a constant, then the field reference is substituted for this constant, otherwise it sets a pointer to the multiple equality in the field item.

Parameters

arg	reference to list of multiple equalities where the field (this object) is to be looked for

Note: This function is supposed to be called as a callback parameter in calls of the compile method.

Returns

pointer to the replacing constant item, if the field item was substituted
pointer to the field item, otherwise.

Reimplemented from Item.

Definition at line 5718 of file item.cc.

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Item_equal * Item_field::find_item_equal ( COND_EQUAL * cond_equal )

Find a field among specified multiple equalities.

The function first searches the field among multiple equalities of the current level (in the cond_equal->current_level list). If it fails, it continues searching in upper levels accessed through a pointer cond_equal->upper_levels. The search terminates as soon as a multiple equality containing the field is found.

Parameters

cond_equal reference to list of multiple equalities where the field (this object) is to be looked for

Returns

First Item_equal containing the field, if success
0, otherwise

Definition at line 5608 of file item.cc.

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bool Item_field::find_item_in_field_list_processor ( uchar * arg )

virtual

Check if an Item_field references some field from a list of fields.

Check whether the Item_field represented by 'this' references any of the fields in the keyparts passed via 'arg'. Used with the method Item::walk() to test whether any keypart in a sequence of keyparts is referenced in an expression.

Parameters

arg	Field being compared, arg must be of type Field

Return values

TRUE	if 'this' references the field 'arg'
FALSE	otherwise

Reimplemented from Item.

Definition at line 924 of file item.cc.

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

virtual

Resolve the name of a column reference.

The method resolves the column reference represented by 'this' as a column present in one of: FROM clause, SELECT clause, GROUP BY clause of a query Q, or in outer queries that contain Q.

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

resolve_column_reference([T_j].col_ref_i)
{
  search for a column or derived column named col_ref_i
  [in table T_j] in the FROM clause 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 FROM clause of Q_k;
      if such a column is not found
        Search for a column or derived column named col_ref_i
        [in table T_j] in the SELECT and GROUP clauses of Q_k.
    }
  }
}

Notice that compared to Item_ref::fix_fields, here we first search the FROM clause, and then we search the SELECT and GROUP BY clauses.

Parameters

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

Return values

TRUE	if error
FALSE	on success

Reimplemented from Item.

Reimplemented in Item_insert_value, and Item_default_value.

Definition at line 5325 of file item.cc.

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int Item_field::fix_outer_field	(	THD *	thd,
		Field **	from_field,
		Item **	reference
	)

Resolve the name of an outer select column reference.

The method resolves the column reference represented by 'this' as a column present in outer selects that contain current select.

In prepared statements, because of cache, find_field_in_tables() can resolve fields even if they don't belong to current context. In this case this method only finds appropriate context and marks current select as dependent. The found reference of field should be provided in 'from_field'.

Parameters

[in]	thd	current thread
[in,out]	from_field	found field reference or (Field*)not_found_field
[in,out]	reference	view column if this item was resolved to a view column

Note: This is the inner loop of Item_field::fix_fields:
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 FROM clause of Q_k;

if such a column is not found

Search for a column or derived column named col_ref_i

[in table T_j] in the SELECT and GROUP clauses of Q_k.

}

Return values

1	column succefully resolved and fix_fields() should continue.
0	column fully fixed and fix_fields() should return FALSE
-1	error occured

Definition at line 5003 of file item.cc.

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bool Item_field::get_timeval	(	struct timeval *	tm,
		int *	warnings
	)

virtual

Get timestamp in "struct timeval" format.

Return values

false	on success
true	on error

Reimplemented from Item.

Definition at line 2752 of file item.cc.

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bool Item_field::item_field_by_name_analyzer ( uchar ** arg )

virtual

Analyzer for finding Item_field by name

Parameters

arg	Field name to search for

Returns: TRUE Go deeper in item tree. (Found Item or not an Item_field); FALSE Don't go deeper in item tree. (Item_field with other name)

Reimplemented from Item.

Definition at line 6960 of file item.cc.

Item * Item_field::item_field_by_name_transformer ( uchar * arg )

virtual

Simple transformer that returns the argument if this is an Item_field. The new item will inherit it's name to maintain aliases.

Parameters

arg	Item to replace Item_field

Returns: argument if this is an Item_field; this otherwise.

Reimplemented from Item.

Definition at line 6971 of file item.cc.

enum Item_result Item_field::numeric_context_result_type ( ) const

inlinevirtual

Result type when an item appear in a numeric context. See Field::numeric_context_result_type() for more comments.

Reimplemented from Item.

Definition at line 2213 of file item.h.

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void Item_field::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_insert_value, and Item_default_value.

Definition at line 7046 of file item.cc.

bool Item_field::remove_column_from_bitmap ( uchar * arg )

virtual

Visitor interface for removing all column expressions (Item_field) in this expression tree from a bitmap. walk()

Parameters

arg	A MY_BITMAP* cast to unsigned char*, where the bits represent Field::field_index values.

Reimplemented from Item.

Definition at line 901 of file item.cc.

Item * Item_field::replace_equal_field ( uchar * arg )

virtual

Replace an Item_field for an equal Item_field that evaluated earlier (if any).

The function returns a pointer to an item that is taken from the very beginning of the item_equal list which the Item_field object refers to (belongs to) unless item_equal contains a constant item. In this case the function returns this constant item, (if the substitution does not require conversion). If the Item_field object does not refer any Item_equal object 'this' is returned .

Parameters

arg	a dummy parameter, is not used here

Note: This function is supposed to be called as a callback parameter in calls of the thransformer method.

Returns

pointer to a replacement Item_field if there is a better equal item or a pointer to a constant equal item;
this - otherwise.

Reimplemented from Item.

Definition at line 5792 of file item.cc.

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void Item_field::reset_field ( Field * f )

Reset this item to point to a field from the new temporary table. This is used when we create a new temporary table for each execution of prepared statement.

Definition at line 2567 of file item.cc.

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table_map Item_field::resolved_used_tables ( ) const

virtual

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 2866 of file item.cc.

type_conversion_status Item_field::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.

Reimplemented in Item_insert_value, and Item_default_value.

Definition at line 6160 of file item.cc.

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void Item_field::save_org_in_field ( Field * to )

virtual

Set a field's value from a item.

Reimplemented from Item.

Definition at line 6144 of file item.cc.

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bool Item_field::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 6979 of file item.cc.

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bool Item_field::set_no_const_sub ( uchar * arg )

virtual

Mark the item to not be part of substitution if it's not a binary item.

See comments in Arg_comparator::set_compare_func() for details.

Reimplemented from Item.

Definition at line 5759 of file item.cc.

bool Item_field::subst_argument_checker ( uchar ** arg )

virtual

Check whether a field can be substituted by an equal item.

The function checks whether a substitution of the field occurrence for an equal item is valid.

Parameters

arg	*arg != NULL <-> the field is in the context where substitution for an equal item is valid

Note: The following statement is not always true:
x=y => F(x)=F(x/y).
This means substitution of an item for an equal item not always yields an equavalent condition. Here's an example:
'a'='a '

(LENGTH('a')=1) != (LENGTH('a ')=2)

Such a substitution is surely valid if either the substituted field is not of a STRING type or if it is an argument of a comparison predicate.

Return values

TRUE	substitution is valid
FALSE	otherwise

Reimplemented from Item.

Definition at line 5659 of file item.cc.

longlong Item_field::val_date_temporal ( )

virtual

Return date value of item in packed longlong format.

Reimplemented from Item.

Definition at line 2696 of file item.cc.

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longlong Item_field::val_date_temporal_result ( )

virtual

Get date value in packed longlong format. NULL is converted to 0.

Reimplemented from Item.

Definition at line 2782 of file item.cc.

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longlong Item_field::val_time_temporal ( )

virtual

Return time value of item in packed longlong format.

Reimplemented from Item.

Definition at line 2687 of file item.cc.

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longlong Item_field::val_time_temporal_result ( )

virtual

Get time value in packed longlong format. NULL is converted to 0.

Reimplemented from Item.

Definition at line 2775 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

Public Member Functions

Public Attributes

Protected Member Functions

Friends

Additional Inherited Members

Detailed Description

Constructor & Destructor Documentation

Member Function Documentation