MySQL  8.0.17
Source Code Documentation
Item_field Class Reference

#include <item.h>

Inheritance diagram for Item_field:
Item_ident Item Parse_tree_node_tmpl< Context > Item_default_value Item_insert_value Item_trigger_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 (const POS &pos, const char *db_arg, const char *table_name_arg, const char *field_name_arg)
 
 Item_field (THD *thd, Item_field *item)
 Constructor need to process subselect with temporary tables (see Item) More...
 
 Item_field (THD *thd, Name_resolution_context *context_arg, Field *field)
 Constructor used inside setup_wild(). More...
 
 Item_field (Field *field)
 
bool itemize (Parse_context *pc, Item **res) override
 The same as contextualize()/contextualize_() but with additional parameter. More...
 
enum Type type () const override
 
bool eq (const Item *item, bool binary_cmp) const override
 
double val_real () override
 
longlong val_int () override
 
longlong val_time_temporal () override
 Return time value of item in packed longlong format. More...
 
longlong val_date_temporal () override
 Return date value of item in packed longlong format. More...
 
my_decimalval_decimal (my_decimal *) override
 
Stringval_str (String *) override
 
bool val_json (Json_wrapper *result) override
 Get a JSON value from an Item. More...
 
bool send (Protocol *protocol, String *str_arg) override
 This is only called from items that is not of type item_field. More...
 
void reset_field (Field *f)
 Reset this item to point to a field from the new temporary table. More...
 
bool fix_fields (THD *, Item **) override
 Resolve the name of a column reference. More...
 
void make_field (Send_field *tmp_field) override
 
void save_org_in_field (Field *field) override
 Set a field's value from a item. More...
 
table_map used_tables () const override
 
enum Item_result result_type () const override
 
enum Item_result numeric_context_result_type () const override
 Result type when an item appear in a numeric context. More...
 
Item_result cast_to_int_type () const override
 
enum_monotonicity_info get_monotonicity_info () const override
 
longlong val_int_endpoint (bool left_endp, bool *incl_endp) override
 
Fieldget_tmp_table_field () override
 
Fieldtmp_table_field (TABLE *) override
 
bool get_date (MYSQL_TIME *ltime, my_time_flags_t fuzzydate) override
 
bool get_time (MYSQL_TIME *ltime) override
 
bool get_timeval (struct timeval *tm, int *warnings) override
 Get timestamp in "struct timeval" format. More...
 
bool is_null () override
 
Itemget_tmp_table_item (THD *thd) override
 
bool collect_item_field_processor (uchar *arg) override
 Store the pointer to this item field into a list if not already there. More...
 
bool add_field_to_set_processor (uchar *arg) override
 Item::walk function. More...
 
bool add_field_to_cond_set_processor (uchar *) override
 Item::walk function. More...
 
bool remove_column_from_bitmap (uchar *arg) override
 Visitor interface for removing all column expressions (Item_field) in this expression tree from a bitmap. More...
 
bool find_item_in_field_list_processor (uchar *arg) override
 Check if an Item_field references some field from a list of fields. More...
 
bool find_field_processor (uchar *arg) override
 Is this an Item_field which references the given Field argument? More...
 
bool check_function_as_value_generator (uchar *args) override
 Check if this item is allowed for a virtual column or inside a default expression. More...
 
bool mark_field_in_map (uchar *arg) override
 Mark underlying field in read or write map of a table. More...
 
bool used_tables_for_level (uchar *arg) override
 Return used table information for the specified query block (level). More...
 
bool check_column_privileges (uchar *arg) override
 Check privileges of base table column. More...
 
bool check_partition_func_processor (uchar *) override
 Check if a partition function is allowed. More...
 
void cleanup () override
 
Item_equalfind_item_equal (COND_EQUAL *cond_equal)
 Find a field among specified multiple equalities. More...
 
bool subst_argument_checker (uchar **arg) override
 Check whether a field can be substituted by an equal item. More...
 
Itemequal_fields_propagator (uchar *arg) override
 Set a pointer to the multiple equality the field reference belongs to (if any). More...
 
bool set_no_const_sub (uchar *) override
 Mark the item to not be part of substitution if it's not a binary item. More...
 
Itemreplace_equal_field (uchar *) override
 Replace an Item_field for an equal Item_field that evaluated earlier (if any). More...
 
uint32 max_disp_length ()
 
Item_fieldfield_for_view_update () override
 
Itemsafe_charset_converter (THD *thd, const CHARSET_INFO *tocs) override
 
int fix_outer_field (THD *thd, Field **field, Item **reference)
 Resolve the name of an outer select column reference. More...
 
Itemupdate_value_transformer (uchar *select_arg) override
 
void print (const THD *thd, String *str, enum_query_type query_type) const override
 This method is used for to: More...
 
bool is_outer_field () const override
 
Field::geometry_type get_geometry_type () const override
 
const CHARSET_INFOcharset_for_protocol (void) const override
 
void dbug_print () const
 
float get_filtering_effect (THD *thd, table_map filter_for_table, table_map read_tables, const MY_BITMAP *fields_to_ignore, double rows_in_table) override
 Calculate condition filtering effect for "WHERE field", which implicitly means "WHERE field <> 0". More...
 
float get_cond_filter_default_probability (double max_distinct_values, float default_filter) const
 Returns the probability for the predicate "col OP <val>" to be true for a row in the case where no index statistics or range estimates are available for 'col'. More...
 
bool alias_name_used () const override
 
bool repoint_const_outer_ref (uchar *arg) override
 If this object is the real_item of an Item_ref, repoint the result_field to field. More...
 
Fieldget_orig_field () override
 
void set_orig_field (Field *orig_field_arg) override
 
bool returns_array () const override
 Whether the item returns array of its data type. More...
 
void set_can_use_prefix_key () override
 
bool replace_field_processor (uchar *arg) override
 A processor that replaces any Fields with a Create_field_wrapper. More...
 
bool strip_db_table_name_processor (uchar *) override
 Generated fields don't need db/table names. More...
 
- 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 (const POS &pos, const char *db_name_arg, const char *table_name_arg, const char *field_name_arg)
 
 Item_ident (THD *thd, Item_ident *item)
 Constructor used by Item_field & Item_*_ref (see Item comment) More...
 
const char * full_name () const override
 
void fix_after_pullout (SELECT_LEX *parent_select, SELECT_LEX *removed_select) override
 Fix after tables have been moved from one select_lex level to the parent level, e.g by semijoin conversion. More...
 
bool aggregate_check_distinct (uchar *arg) override
 
bool aggregate_check_group (uchar *arg) override
 
Bool3 local_column (const SELECT_LEX *sl) const override
 Tells if this is a column of a table whose qualifying query block is 'sl'. More...
 
bool set_table_name (uchar *tn) override final
 Assign the argument to table_name. More...
 
bool change_context_processor (uchar *cntx) override
 
bool is_alias_of_expr () const
 
void set_alias_of_expr ()
 Marks that this Item's name is alias of SELECT expression. More...
 
bool walk (Item_processor processor, enum_walk walk, uchar *arg) override
 Traverses a tree of Items in prefix and/or postfix order. More...
 
bool is_strong_side_column_not_in_fd (uchar *arg) override
 
bool is_column_not_in_fd (uchar *arg) override
 
- Public Member Functions inherited from Item
 Item (const Item &)=delete
 
void operator= (Item &)=delete
 
 Item ()
 Item constructor for general use. More...
 
 Item (THD *thd, Item *item)
 Constructor used by Item_field, Item_ref & aggregate functions. More...
 
 Item (const POS &)
 Parse-time context-independent constructor. More...
 
virtual ~Item () override
 
void rename (char *new_name)
 rename item (used for views, cleanup() return original name). More...
 
void init_make_field (Send_field *tmp_field, enum enum_field_types type)
 
virtual Fieldmake_string_field (TABLE *table)
 Create a field to hold a string value from an item. More...
 
void quick_fix_field ()
 
type_conversion_status save_in_field_no_warnings (Field *field, bool no_conversions)
 Save the item into a field but do not emit any warnings. More...
 
type_conversion_status save_in_field (Field *field, bool no_conversions)
 Save a temporal value in packed longlong format into a Field. More...
 
bool evaluate (THD *thd, String *str)
 Evaluate item, possibly using the supplied buffer. More...
 
enum Item_result temporal_with_date_as_number_result_type () const
 Similar to result_type() but makes DATE, DATETIME, TIMESTAMP pretend to be numbers rather than strings. More...
 
enum_field_types data_type () const
 Retrieve the derived data type of the Item. More...
 
void set_data_type (enum_field_types data_type)
 Set the data type of the current Item. More...
 
void set_data_type_bool ()
 
void set_data_type_longlong ()
 Set the data type of the Item to be longlong. More...
 
void set_data_type_decimal (uint8 precision, uint8 dec)
 Set the data type of the Item to be decimal. More...
 
void set_data_type_double ()
 Set the data type of the Item to be double precision floating point. More...
 
void set_data_type_float ()
 Set the data type of the Item to be single precision floating point. More...
 
void set_data_type_string_init ()
 Initialize an Item to be of VARCHAR type, other properties undetermined. More...
 
void set_data_type_string (uint32 max_l)
 Set the Item to be variable length string. More...
 
void set_data_type_string (ulonglong max_char_length_arg)
 Set the Item to be variable length string. More...
 
void set_data_type_string (ulonglong max_l, const CHARSET_INFO *cs)
 Set the Item to be variable length string. More...
 
void set_data_type_string (uint32 max_l, const DTCollation &coll)
 Set the Item to be variable length string. More...
 
void set_data_type_char (uint32 max_l)
 Set the Item to be fixed length string. More...
 
void set_data_type_char (uint32 max_l, const CHARSET_INFO *cs)
 Set the Item to be fixed length string. More...
 
void set_data_type_blob (uint32 max_l)
 Set the Item to be of BLOB type. More...
 
void set_data_type_date ()
 Set all type properties for Item of DATE type. More...
 
void set_data_type_time (uint8 fsp)
 Set all type properties for Item of TIME type. More...
 
void set_data_type_datetime (uint8 fsp)
 Set all properties for Item of DATETIME type. More...
 
void set_data_type_timestamp (uint8 fsp)
 Set all properties for Item of TIMESTAMP type. More...
 
void set_data_type_json ()
 Set the data type of the Item to be JSON. More...
 
void set_data_type_year ()
 Set the data type of the Item to be YEAR. More...
 
void set_data_type_geometry ()
 Set the Item to be of GEOMETRY type. More...
 
void set_data_type_from_result (Item_result result, uint32 length)
 Set type information of Item from "result" information. More...
 
void set_data_type_from_item (Item *item)
 Set data type properties of the item from the properties of another item. More...
 
void aggregate_type (Bounds_checked_array< Item *> items)
 Aggregates data types from array of items into current item. More...
 
bool is_null_value ()
 For template-compatibility with Field. More...
 
longlong val_temporal_by_field_type ()
 Return date or time value of item in packed longlong format, depending on item field type. More...
 
longlong val_temporal_with_round (enum_field_types type, uint8 dec)
 Get date or time value in packed longlong format. More...
 
ulonglong val_uint ()
 
virtual Stringval_str_ascii (String *str)
 
virtual bool val_bool ()
 
bool error_json ()
 Get the value to return from val_json() in case of errors. More...
 
bool get_date_from_non_temporal (MYSQL_TIME *ltime, my_time_flags_t fuzzydate)
 Convert a non-temporal type to date. More...
 
bool get_time_from_non_temporal (MYSQL_TIME *ltime)
 Convert a non-temporal type to time. More...
 
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 Itemclone_item () const
 
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 ()
 TIME precision of the item: 0..6. More...
 
virtual uint datetime_precision ()
 DATETIME precision of the item: 0..6. More...
 
bool const_item () const
 Returns true if item is constant, regardless of query evaluation state. More...
 
bool const_for_execution () const
 Returns true if item is constant during one query execution. More...
 
bool may_evaluate_const (const THD *thd) const
 Return true if this is a const item that may be evaluated in the current phase of statement processing. More...
 
void print_item_w_name (const THD *thd, String *, enum_query_type query_type) const
 
void print_for_order (const THD *thd, String *str, enum_query_type query_type, bool used_alias) const
 Prints the item when it's part of ORDER BY and GROUP BY. More...
 
virtual void update_used_tables ()
 
virtual void split_sum_func (THD *, Ref_item_array, List< Item > &)
 
void split_sum_func2 (THD *thd, Ref_item_array ref_item_array, List< Item > &fields, Item **ref, bool skip_registered)
 
bool update_null_value ()
 Make sure the null_value member has a correct value. More...
 
virtual void apply_is_true ()
 Apply the IS TRUE truth property, meaning that an UNKNOWN result and a FALSE result are treated the same. More...
 
virtual void set_result_field (Field *)
 
virtual bool is_result_field () const
 
virtual Fieldget_result_field () const
 
virtual bool is_bool_func () const
 
virtual void save_in_result_field (bool no_conversions)
 
virtual void no_rows_in_result ()
 
virtual Itemcopy_or_same (THD *)
 
virtual Itemcopy_andor_structure (THD *)
 
virtual Itemreal_item ()
 
virtual Itemsubstitutional_item ()
 
virtual void set_runtime_created ()
 
virtual const CHARSET_INFOcompare_collation () const
 
template<class T >
bool walk_helper_thunk (uchar *arg)
 
virtual Itemtransform (Item_transformer transformer, uchar *arg)
 Perform a generic transformation of the Item tree, by adding zero or more additional Item objects to it. More...
 
virtual Itemcompile (Item_analyzer analyzer, uchar **arg_p, Item_transformer transformer, uchar *arg_t)
 Perform a generic "compilation" of the Item tree, ie transform the Item tree by adding zero or more Item objects to it. More...
 
virtual void traverse_cond (Cond_traverser traverser, void *arg, traverse_order)
 
virtual bool intro_version (uchar *)
 
bool cleanup_processor (uchar *)
 cleanup() item if it is resolved ('fixed'). More...
 
virtual bool visitor_processor (uchar *arg)
 A processor to handle the select lex visitor framework. More...
 
virtual bool find_item_processor (uchar *arg)
 
virtual bool is_non_const_over_literals (uchar *)
 
virtual bool references_select_expr_of (uchar *arg)
 
virtual bool reset_wf_state (uchar *arg)
 Reset execution state for such window function types as determined by arg. More...
 
virtual bool inform_item_in_cond_of_tab (uchar *)
 
virtual bool clean_up_after_removal (uchar *arg)
 Clean up after removing the item from the item tree. More...
 
bool propagate_derived_used (uchar *)
 Propagate components that use referenced columns from derived tables. More...
 
bool propagate_set_derived_used (uchar *)
 Called by Item::walk() to set all the referenced items' derived_used flag. More...
 
virtual bool has_aggregate_ref_in_group_by (uchar *)
 Check if an aggregate is referenced from within the GROUP BY clause of the query block in which it is aggregated. More...
 
virtual bool cache_const_expr_analyzer (uchar **cache_item)
 Check if an item is a constant one and can be cached. More...
 
Itemcache_const_expr_transformer (uchar *item)
 Cache item if needed. More...
 
virtual bool equality_substitution_analyzer (uchar **)
 
virtual Itemequality_substitution_transformer (uchar *)
 
virtual bool explain_subquery_checker (uchar **)
 
virtual Itemexplain_subquery_propagator (uchar *)
 
virtual bool check_valid_arguments_processor (uchar *)
 
virtual bool check_gcol_depend_default_processor (uchar *args)
 Check if a generated expression depends on DEFAULT function with specific column name as argument. More...
 
virtual Itemthis_item ()
 
virtual const Itemthis_item () const
 
virtual Item ** this_item_addr (THD *, Item **addr_arg)
 
virtual uint cols () const
 
virtual Itemelement_index (uint)
 
virtual Item ** addr (uint)
 
virtual bool check_cols (uint c)
 
virtual bool null_inside ()
 
virtual void bring_value ()
 
Fieldtmp_table_field_from_field_type (TABLE *table, bool fixed_length)
 Create a field based on field_type of argument. More...
 
virtual Itemtruth_transformer (THD *thd, Bool_test test)
 Informs an item that it is wrapped in a truth test, in case it wants to transforms itself to implement this test by itself. More...
 
void delete_self ()
 
virtual bool is_splocal () const
 
virtual Settable_routine_parameterget_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
 Check whether this and the given item has compatible comparison context. More...
 
Stringcheck_well_formed_result (String *str, bool send_error, bool truncate)
 Verifies that the input string is well-formed according to its character set. More...
 
bool eq_by_collation (Item *item, bool binary_cmp, const CHARSET_INFO *cs)
 
virtual bool is_expensive ()
 
uint32 max_char_length () const
 
void fix_char_length (uint32 max_char_length_arg)
 
bool is_blob_field () const
 Check if an item either is a blob field, or will be represented as a BLOB field if a field is created based on this item. More...
 
bool has_subquery () const
 
bool has_stored_program () const
 
bool has_aggregation () const
 
void set_aggregation ()
 Set the "has aggregation" property. More...
 
void reset_aggregation ()
 Reset the "has aggregation" property. More...
 
bool has_wf () const
 
void set_wf ()
 Set the "has window function" property. More...
 
bool has_rollup_expr () const
 
void set_rollup_expr ()
 Set the property: this item (tree) contains a reference to a ROLLUP expr. More...
 
bool has_grouping_func () const
 
void set_grouping_func ()
 Set the property: this item is a call to GROUPING. More...
 
virtual bool created_by_in2exists () const
 Whether this Item was created by the IN->EXISTS subquery transformation. More...
 
bool is_derived_used () const
 
void mark_subqueries_optimized_away ()
 
virtual bool gc_subst_analyzer (uchar **)
 Analyzer function for GC substitution. More...
 
virtual Itemgc_subst_transformer (uchar *)
 Transformer function for GC substitution. More...
 
bool can_be_substituted_for_gc () const
 Check if this item is of a type that is eligible for GC substitution. More...
 
void aggregate_decimal_properties (Item **item, uint nitems)
 Set precision and decimals of function when this depends on arguments' values for these quantities. More...
 
void aggregate_float_properties (Item **item, uint nitems)
 Set max_length and decimals of function if function is floating point and result length/precision depends on argument ones. More...
 
void aggregate_char_length (Item **args, uint nitems)
 Set the maximum number of characters required by any of the items in args. More...
 
void aggregate_temporal_properties (Item **item, uint nitems)
 Set fractional seconds precision for temporal functions. More...
 
bool aggregate_string_properties (const char *name, Item **item, uint nitems)
 Aggregate string properties (character set, collation and maximum length) for string function. More...
 
void aggregate_num_type (Item_result result_type, Item **item, uint nitems)
 This function is used to resolve type for numeric result type of CASE, COALESCE, IF and LEAD/LAG. More...
 
virtual bool supports_partial_update (const Field_json *field) const
 Check if this expression can be used for partial update of a given JSON column. More...
 
virtual void allow_array_cast ()
 
A helper funciton to ensure proper usage of CAST(. More...
 
- Public Member Functions inherited from Parse_tree_node_tmpl< Context >
virtual ~Parse_tree_node_tmpl ()
 
bool is_contextualized () const
 
virtual bool contextualize (Context *pc)
 Do all context-sensitive things and mark the node as contextualized. More...
 
virtual bool contextualize_ (Context *)
 
Intermediate version of the contextualize() function More...
 
void error (Context *pc, const POS &pos) const
 syntax_error() function replacement for deferred reporting of syntax errors More...
 
void error (Context *pc, const POS &pos, const char *msg) const
 syntax_error() function replacement for deferred reporting of syntax errors More...
 
void errorf (Context *pc, const POS &pos, const char *format,...) const
 syntax_error() function replacement for deferred reporting of syntax errors More...
 

Public Attributes

TABLE_LISTtable_ref
 Table containing this resolved field. More...
 
Fieldfield
 Source field. More...
 
Fieldorig_field
 Item's original field. More...
 
Fieldresult_field
 Result field. More...
 
Item_equalitem_equal
 
bool no_const_subst
 
uint have_privileges
 
bool any_privileges
 
bool can_use_prefix_key {false}
 
- Public Attributes inherited from Item_ident
Name_resolution_contextcontext
 For regularly resolved column references, 'context' points to a name resolution context object belonging to the query block which simply contains the reference. More...
 
const char * db_name
 
const char * table_name
 
const char * field_name
 
uint cached_field_index
 
TABLE_LISTcached_table
 
SELECT_LEXdepended_from
 
- Public Attributes inherited from Item
Itemnext_free
 Intrusive list pointer for free list. More...
 
DTCollation collation
 Character set and collation properties assigned for this Item. More...
 
Item_name_string item_name
 Name from query. More...
 
Item_name_string orig_name
 Original item name (if it was renamed) More...
 
uint32 max_length
 Maximum length of result of evaluating this item, in number of bytes. More...
 
item_marker marker
 This member has several successive meanings, depending on the phase we're in: More...
 
Item_result cmp_context
 Comparison context. More...
 
bool fixed
 True if item has been resolved. More...
 
uint8 decimals
 Number of decimals in result when evaluating this item. More...
 
bool maybe_null
 True if this item may be null. More...
 
bool null_value
 True if item is null. More...
 
bool unsigned_flag
 
bool m_is_window_function
 True if item represents window func. More...
 

Protected Member Functions

void set_field (Field *field)
 
type_conversion_status save_in_field_inner (Field *field, bool no_conversions) override
 Helper function which does all of the work for save_in_field(Field*, bool), except some error checking common to all subclasses, which is performed by save_in_field() itself. More...
 
- Protected Member Functions inherited from Item_ident
void print (const THD *thd, String *str, enum_query_type query_type, const char *db_name_arg, const char *table_name_arg) const
 Function to print column name for a table. More...
 
- Protected Member Functions inherited from Item
Stringmake_empty_result ()
 Sets the result value of the function an empty string, using the current character set. More...
 
bool skip_itemize (Item **res)
 Helper function to skip itemize() for grammar-allocated items. More...
 
Stringval_string_from_real (String *str)
 
Stringval_string_from_int (String *str)
 
Stringval_string_from_decimal (String *str)
 
Stringval_string_from_date (String *str)
 
Stringval_string_from_datetime (String *str)
 
Stringval_string_from_time (String *str)
 
my_decimalval_decimal_from_real (my_decimal *decimal_value)
 
my_decimalval_decimal_from_int (my_decimal *decimal_value)
 
my_decimalval_decimal_from_string (my_decimal *decimal_value)
 
my_decimalval_decimal_from_date (my_decimal *decimal_value)
 
my_decimalval_decimal_from_time (my_decimal *decimal_value)
 
longlong val_int_from_decimal ()
 
longlong val_int_from_date ()
 
longlong val_int_from_time ()
 
longlong val_int_from_datetime ()
 
double val_real_from_decimal ()
 
bool error_bool ()
 Get the value to return from val_bool() in case of errors. More...
 
int error_int ()
 Get the value to return from val_int() in case of errors. More...
 
double error_real ()
 Get the value to return from val_real() in case of errors. More...
 
Stringerror_str ()
 Get the value to return from val_str() in case of errors. More...
 
Stringnull_return_str ()
 Gets the value to return from val_str() when returning a NULL value. More...
 
bool get_date_from_string (MYSQL_TIME *ltime, my_time_flags_t flags)
 Convert val_str() to date in MYSQL_TIME. More...
 
bool get_date_from_real (MYSQL_TIME *ltime, my_time_flags_t flags)
 Convert val_real() to date in MYSQL_TIME. More...
 
bool get_date_from_decimal (MYSQL_TIME *ltime, my_time_flags_t flags)
 Convert val_decimal() to date in MYSQL_TIME. More...
 
bool get_date_from_int (MYSQL_TIME *ltime, my_time_flags_t flags)
 Convert val_int() to date in MYSQL_TIME. More...
 
bool get_date_from_time (MYSQL_TIME *ltime)
 Convert get_time() from time to date in MYSQL_TIME. More...
 
bool get_date_from_numeric (MYSQL_TIME *ltime, my_time_flags_t fuzzydate)
 Convert a numeric type to date. More...
 
bool get_time_from_string (MYSQL_TIME *ltime)
 Convert val_str() to time in MYSQL_TIME. More...
 
bool get_time_from_real (MYSQL_TIME *ltime)
 Convert val_real() to time in MYSQL_TIME. More...
 
bool get_time_from_decimal (MYSQL_TIME *ltime)
 Convert val_decimal() to time in MYSQL_TIME. More...
 
bool get_time_from_int (MYSQL_TIME *ltime)
 Convert val_int() to time in MYSQL_TIME. More...
 
bool get_time_from_date (MYSQL_TIME *ltime)
 Convert date to time. More...
 
bool get_time_from_datetime (MYSQL_TIME *ltime)
 Convert datetime to time. More...
 
bool get_time_from_numeric (MYSQL_TIME *ltime)
 Convert a numeric type to time. More...
 
void set_accum_properties (const Item *item)
 Set accumulated properties for an Item. More...
 
void add_accum_properties (const Item *item)
 Add more accumulated properties to an Item. More...
 
void set_subquery ()
 Set the "has subquery" property. More...
 
void set_stored_program ()
 Set the "has stored program" property. More...
 
- Protected Member Functions inherited from Parse_tree_node_tmpl< Context >
 Parse_tree_node_tmpl ()
 

Private Types

typedef Item_ident super
 

Friends

class Item_default_value
 
class Item_insert_value
 
class SELECT_LEX_UNIT
 

Additional Inherited Members

- Public Types inherited from Item
enum  Type {
  INVALID_ITEM = 0, FIELD_ITEM, 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,
  FIELD_BIT_ITEM, NULL_RESULT_ITEM
}
 
enum  cond_result { COND_UNDEF, COND_OK, COND_TRUE, COND_FALSE }
 
enum  traverse_order { POSTFIX, PREFIX }
 
enum  enum_const_item_cache { CACHE_NONE = 0, CACHE_JSON_VALUE, CACHE_JSON_ATOM }
 How to cache constant JSON data. More...
 
enum  Bool_test {
  BOOL_IS_TRUE = 0x00, BOOL_IS_FALSE = 0x01, BOOL_IS_UNKNOWN = 0x02, BOOL_NOT_TRUE = 0x03,
  BOOL_NOT_FALSE = 0x04, BOOL_NOT_UNKNOWN = 0x05, BOOL_IDENTITY = 0x06, BOOL_NEGATED = 0x07,
  BOOL_ALWAYS_TRUE = 0x08, BOOL_ALWAYS_FALSE = 0x09
}
 < Modifier for result transformation More...
 
enum  item_marker {
  MARKER_NONE = 0, MARKER_CONST_PROPAG = 1, MARKER_BIT = 4, MARKER_FUNC_DEP_NOT_NULL = 5,
  MARKER_DISTINCT_GROUP = 6, MARKER_ICP_COND_USES_INDEX_ONLY = 10
}
 < Values for member 'marker' More...
 
- Public Types inherited from Parse_tree_node_tmpl< Context >
typedef Context context_t
 
- Static Public Member Functions inherited from Item
static void * operator new (size_t size) noexcept
 
static void * operator new (size_t size, MEM_ROOT *mem_root, const std::nothrow_t &arg=std::nothrow) noexcept
 
static void operator delete (void *ptr, size_t size)
 
static void operator delete (void *, MEM_ROOT *, const std::nothrow_t &) noexcept
 
static enum_field_types type_for_variable (enum_field_types src_type)
 Provide data type for a user or system variable, based on the type of the item that is assigned to the variable. More...
 
static enum_field_types string_field_type (uint32 max_bytes)
 Determine correct string field type, based on string length. More...
 
static const CHARSET_INFOdefault_charset ()
 
- Static Public Member Functions inherited from Parse_tree_node_tmpl< Context >
static void * operator new (size_t size, MEM_ROOT *mem_root, const std::nothrow_t &arg=std::nothrow) noexcept
 
static void operator delete (void *ptr, size_t size)
 
static void operator delete (void *, MEM_ROOT *, const std::nothrow_t &) noexcept
 
- Static Protected Member Functions inherited from Item
static bool bit_func_returns_binary (const Item *a, const Item *b)
 
static bool mark_field_in_map (Mark_field *mark_field, Field *field)
 Helper function for mark_field_in_map(uchar *arg). More...
 
- Protected Attributes inherited from Item_ident
const char * orig_db_name
 
const char * orig_table_name
 
const char * orig_field_name
 
bool m_alias_of_expr
 if this Item's name is alias of SELECT expression More...
 
- Protected Attributes inherited from Item
String str_value
 str_values's main purpose is to cache the value in save_in_field More...
 
uint8 m_accum_properties
 
- Static Protected Attributes inherited from Item
static constexpr uint8 PROP_SUBQUERY = 0x01
 Set of properties that are calculated by accumulation from underlying items. More...
 
static constexpr uint8 PROP_STORED_PROGRAM = 0x02
 
static constexpr uint8 PROP_AGGREGATION = 0x04
 
static constexpr uint8 PROP_WINDOW_FUNCTION = 0x08
 
static constexpr uint8 PROP_ROLLUP_EXPR = 0x10
 Set if the item or one or more of the underlying items contains a ROLLUP expression. More...
 
static constexpr uint8 PROP_GROUPING_FUNC = 0x20
 Set if the item or one or more of the underlying items is a GROUPING function. More...
 

Member Typedef Documentation

◆ super

typedef Item_ident Item_field::super
private

Constructor & Destructor Documentation

◆ Item_field() [1/5]

Item_field::Item_field ( Name_resolution_context context_arg,
const char *  db_arg,
const char *  table_name_arg,
const char *  field_name_arg 
)

◆ Item_field() [2/5]

Item_field::Item_field ( const POS pos,
const char *  db_arg,
const char *  table_name_arg,
const char *  field_name_arg 
)

◆ Item_field() [3/5]

Item_field::Item_field ( THD thd,
Item_field item 
)

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

◆ Item_field() [4/5]

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).

◆ Item_field() [5/5]

Item_field::Item_field ( Field field)

Member Function Documentation

◆ add_field_to_cond_set_processor()

bool Item_field::add_field_to_cond_set_processor ( uchar )
overridevirtual

Item::walk function.

Set bit in table->cond_set for all fields of all tables that are referred to by the Item.

Reimplemented from Item.

◆ add_field_to_set_processor()

bool Item_field::add_field_to_set_processor ( uchar )
overridevirtual

Item::walk function.

Set bit in table->tmp_set for all fields in table 'arg' that are referred to by the Item.

Reimplemented from Item.

◆ alias_name_used()

bool Item_field::alias_name_used ( ) const
inlineoverridevirtual
Note
that field->table->alias_name_used is reliable only if thd->lex->need_correct_ident() is true.

Reimplemented from Item_ident.

◆ cast_to_int_type()

Item_result Item_field::cast_to_int_type ( ) const
inlineoverridevirtual

Reimplemented from Item.

◆ charset_for_protocol()

const CHARSET_INFO* Item_field::charset_for_protocol ( void  ) const
inlineoverridevirtual

Reimplemented from Item.

◆ check_column_privileges()

bool Item_field::check_column_privileges ( uchar arg)
overridevirtual

Check privileges of base table column.

Reimplemented from Item.

◆ check_function_as_value_generator()

bool Item_field::check_function_as_value_generator ( uchar args)
overridevirtual

Check if this item is allowed for a virtual column or inside a default expression.

Should be overridden in child classes.

Parameters
[in,out]argsDue to the limitation of Item::walk() it is declared as a pointer to uchar, underneath there's a actually a structure of type Check_function_as_value_generator_parameters. It is used mainly in Item_field.
Returns
true if function is not accepted

Reimplemented from Item.

Reimplemented in Item_trigger_field, and Item_insert_value.

◆ check_partition_func_processor()

bool Item_field::check_partition_func_processor ( uchar )
inlineoverridevirtual

Check if a partition function is allowed.

Returns
whether a partition function is not accepted

check_partition_func_processor is used to check if a partition function uses an allowed function. An allowed function will always ensure that X=Y guarantees that also part_function(X)=part_function(Y) where X is a set of partition fields and so is Y. The problems comes mainly from character sets where two equal strings can be quite unequal. E.g. the german character for double s is equal to 2 s.

The default is that an item is not allowed in a partition function. Allowed functions can never depend on server version, they cannot depend on anything related to the environment. They can also only depend on a set of fields in the table itself. They cannot depend on other tables and cannot contain any queries and cannot contain udf's or similar. If a new Item class is defined and it inherits from a class that is allowed in a partition function then it is very important to consider whether this should be inherited to the new class. If not the function below should be defined in the new Item class.

The general behaviour is that most integer functions are allowed. If the partition function contains any multi-byte collations then the function check_part_func_fields will report an error on the partition function independent of what functions are used. So the only character sets allowed are single character collation and even for those only a limited set of functions are allowed. The problem with multi-byte collations is that almost every string function has the ability to change things such that two strings that are equal will not be equal after manipulated by a string function. E.g. two strings one contains a double s, there is a special german character that is equal to two s. Now assume a string function removes one character at this place, then in one the double s will be removed and in the other there will still be one s remaining and the strings are no longer equal and thus the partition function will not sort equal strings into the same partitions.

So the check if a partition function is valid is two steps. First check that the field types are valid, next check that the partition function is valid. The current set of partition functions valid assumes that there are no multi-byte collations amongst the partition fields.

Reimplemented from Item.

◆ cleanup()

void Item_field::cleanup ( )
overridevirtual

Reimplemented from Item_ident.

Reimplemented in Item_trigger_field.

◆ collect_item_field_processor()

bool Item_field::collect_item_field_processor ( uchar arg)
overridevirtual

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
argpointer to a List<Item_field>
Returns
false to force the evaluation of collect_item_field_processor for the subsequent items.

Reimplemented from Item.

◆ dbug_print()

void Item_field::dbug_print ( ) const
inline

◆ eq()

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

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_trigger_field, Item_insert_value, and Item_default_value.

◆ equal_fields_propagator()

Item * Item_field::equal_fields_propagator ( uchar arg)
overridevirtual

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
argreference 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.

◆ field_for_view_update()

Item_field* Item_field::field_for_view_update ( )
inlineoverridevirtual

Reimplemented from Item.

◆ find_field_processor()

bool Item_field::find_field_processor ( uchar )
inlineoverridevirtual

Is this an Item_field which references the given Field argument?

Reimplemented from Item.

◆ find_item_equal()

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_equalreference 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

◆ find_item_in_field_list_processor()

bool Item_field::find_item_in_field_list_processor ( uchar arg)
overridevirtual

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
argField being compared, arg must be of type Field
Return values
trueif 'this' references the field 'arg'
falseotherwise

Reimplemented from Item.

◆ fix_fields()

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

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]thdcurrent thread
[in,out]referenceview column if this item was resolved to a view column
Return values
trueif error
falseon success

Reimplemented from Item.

Reimplemented in Item_trigger_field, Item_insert_value, and Item_default_value.

◆ fix_outer_field()

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]thdcurrent thread
[in,out]from_fieldfound field reference or (Field*)not_found_field
[in,out]referenceview 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
1column succefully resolved and fix_fields() should continue.
0column fully fixed and fix_fields() should return false
-1error occurred

◆ get_cond_filter_default_probability()

float Item_field::get_cond_filter_default_probability ( double  max_distinct_values,
float  default_filter 
) const

Returns the probability for the predicate "col OP <val>" to be true for a row in the case where no index statistics or range estimates are available for 'col'.

The probability depends on the number of rows in the table: it is by default 'default_filter', but never lower than 1/max_distinct_values (e.g. number of rows in the table, or the number of distinct values possible for the datatype if the field provides that kind of information).

Parameters
max_distinct_valuesThe maximum number of distinct values, typically the number of rows in the table
default_filterThe default filter for the predicate
Returns
the estimated filtering effect for this predicate

◆ get_date()

bool Item_field::get_date ( MYSQL_TIME ltime,
my_time_flags_t  fuzzydate 
)
overridevirtual

Implements Item.

◆ get_filtering_effect()

float Item_field::get_filtering_effect ( THD thd,
table_map  filter_for_table,
table_map  read_tables,
const MY_BITMAP fields_to_ignore,
double  rows_in_table 
)
overridevirtual

Calculate condition filtering effect for "WHERE field", which implicitly means "WHERE field <> 0".

The filtering effect is therefore identical to that of Item_func_ne.

Reimplemented from Item.

◆ get_geometry_type()

Field::geometry_type Item_field::get_geometry_type ( ) const
inlineoverridevirtual

Reimplemented from Item.

◆ get_monotonicity_info()

enum_monotonicity_info Item_field::get_monotonicity_info ( ) const
inlineoverridevirtual

Reimplemented from Item.

◆ get_orig_field()

Field* Item_field::get_orig_field ( )
inlineoverridevirtual

Reimplemented from Item.

◆ get_time()

bool Item_field::get_time ( MYSQL_TIME ltime)
overridevirtual

Implements Item.

◆ get_timeval()

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

Get timestamp in "struct timeval" format.

If argument is NULL, sets null_value.

Return values
falseon success
trueon error

Otherwise: if invalid DATETIME value, or a valid DATETIME value but which is out of the supported Unix timestamp range, sets 'tm' to 0.

Reimplemented from Item.

◆ get_tmp_table_field()

Field* Item_field::get_tmp_table_field ( )
inlineoverridevirtual

Reimplemented from Item.

Reimplemented in Item_trigger_field.

◆ get_tmp_table_item()

Item * Item_field::get_tmp_table_item ( THD thd)
overridevirtual

Reimplemented from Item.

Reimplemented in Item_trigger_field, and Item_default_value.

◆ is_null()

bool Item_field::is_null ( )
inlineoverridevirtual

Reimplemented from Item.

◆ is_outer_field()

bool Item_field::is_outer_field ( ) const
inlineoverridevirtual

Reimplemented from Item.

◆ itemize()

bool Item_field::itemize ( Parse_context pc,
Item **  res 
)
overridevirtual

The same as contextualize()/contextualize_() but with additional parameter.

This function finalize the construction of Item objects (see the Item(POS) constructor): we can access/change parser contexts from the itemize() function.

Parameters
pccurrent parse context
[out]respointer to "this" or to a newly allocated replacement object to use in the Item tree instead
Return values
falsesuccess
truesyntax/OOM/etc error

Reimplemented from Item_ident.

Reimplemented in Item_insert_value, and Item_default_value.

◆ make_field()

void Item_field::make_field ( Send_field tmp_field)
overridevirtual

Reimplemented from Item.

◆ mark_field_in_map()

bool Item_field::mark_field_in_map ( uchar arg)
inlineoverridevirtual

Mark underlying field in read or write map of a table.

Parameters
argMark_field object

Reimplemented from Item.

◆ max_disp_length()

uint32 Item_field::max_disp_length ( )
inline

◆ numeric_context_result_type()

enum Item_result Item_field::numeric_context_result_type ( ) const
inlineoverridevirtual

Result type when an item appear in a numeric context.

See Field::numeric_context_result_type() for more comments.

Reimplemented from Item.

◆ print()

void Item_field::print ( const THD ,
String str,
enum_query_type   
) const
overridevirtual

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;
  • to generate a SQL-query that looks like a prepared statement for query_rewrite
  • 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_trigger_field, Item_insert_value, and Item_default_value.

◆ remove_column_from_bitmap()

bool Item_field::remove_column_from_bitmap ( uchar arg)
overridevirtual

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

See also
walk()
Parameters
argA MY_BITMAP* cast to unsigned char*, where the bits represent Field::field_index values.

Reimplemented from Item.

◆ replace_equal_field()

Item * Item_field::replace_equal_field ( uchar )
overridevirtual

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 .

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.

◆ replace_field_processor()

bool Item_field::replace_field_processor ( uchar )
overridevirtual

A processor that replaces any Fields with a Create_field_wrapper.

This will allow us to resolve functions during CREATE TABLE, where we only have Create_field available and not Field. Used for functional index implementation.

Reimplemented from Item.

◆ repoint_const_outer_ref()

bool Item_field::repoint_const_outer_ref ( uchar arg)
overridevirtual

If this object is the real_item of an Item_ref, repoint the result_field to field.

Reimplemented from Item.

◆ reset_field()

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.

◆ result_type()

enum Item_result Item_field::result_type ( ) const
inlineoverridevirtual

Reimplemented from Item.

◆ returns_array()

bool Item_field::returns_array ( ) const
inlineoverridevirtual

Whether the item returns array of its data type.

Reimplemented from Item.

◆ safe_charset_converter()

Item * Item_field::safe_charset_converter ( THD thd,
const CHARSET_INFO tocs 
)
overridevirtual

Reimplemented from Item.

◆ save_in_field_inner()

type_conversion_status Item_field::save_in_field_inner ( Field field,
bool  no_conversions 
)
overrideprotectedvirtual

Helper function which does all of the work for save_in_field(Field*, bool), except some error checking common to all subclasses, which is performed by save_in_field() itself.

Subclasses that need to specialize the behaviour of save_in_field(), should override this function instead of save_in_field().

Parameters
[in,out]fieldthe field to save the item into
no_conversionswhether or not to allow conversions of the value
Returns
the status from saving into the field
Return values
TYPE_OKitem saved without any errors or warnings
!=TYPE_OK there were errors or warnings when saving the item

Reimplemented from Item.

Reimplemented in Item_insert_value, and Item_default_value.

◆ save_org_in_field()

void Item_field::save_org_in_field ( Field field)
overridevirtual

Set a field's value from a item.

Reimplemented from Item.

◆ send()

bool Item_field::send ( Protocol protocol,
String str 
)
overridevirtual

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

Reimplemented from Item.

◆ set_can_use_prefix_key()

void Item_field::set_can_use_prefix_key ( )
inlineoverridevirtual

Reimplemented from Item.

◆ set_field()

void Item_field::set_field ( Field field)
protected

◆ set_no_const_sub()

bool Item_field::set_no_const_sub ( uchar )
overridevirtual

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.

◆ set_orig_field()

void Item_field::set_orig_field ( Field orig_field_arg)
inlineoverridevirtual

Reimplemented from Item.

◆ strip_db_table_name_processor()

bool Item_field::strip_db_table_name_processor ( uchar )
overridevirtual

Generated fields don't need db/table names.

Strip them off as inplace ALTER can reallocate them, making pointers invalid.

Reimplemented from Item.

◆ subst_argument_checker()

bool Item_field::subst_argument_checker ( uchar **  arg)
overridevirtual

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
truesubstitution is valid
falseotherwise

Reimplemented from Item.

◆ tmp_table_field()

Field* Item_field::tmp_table_field ( TABLE )
inlineoverridevirtual

Reimplemented from Item.

◆ type()

enum Type Item_field::type ( ) const
inlineoverridevirtual

Implements Item.

Reimplemented in Item_trigger_field, Item_insert_value, and Item_default_value.

◆ update_value_transformer()

Item * Item_field::update_value_transformer ( uchar select_arg)
overridevirtual

Reimplemented from Item.

◆ used_tables()

table_map Item_field::used_tables ( ) const
overridevirtual

Reimplemented from Item.

Reimplemented in Item_trigger_field, Item_insert_value, and Item_default_value.

◆ used_tables_for_level()

bool Item_field::used_tables_for_level ( uchar arg)
overridevirtual

Return used table information for the specified query block (level).

For a field that is resolved from this query block, return the table number. For a field that is resolved from a query block outer to the specified one, return OUTER_REF_TABLE_BIT

Parameters
[in,out]argpointer to an instance of class Used_tables, which is constructed with the query block as argument. The used tables information is accumulated in the field used_tables in this class.
Note
This function is used to update used tables information after merging a query block (a subquery) with its parent.

Reimplemented from Item.

◆ val_date_temporal()

longlong Item_field::val_date_temporal ( )
overridevirtual

Return date value of item in packed longlong format.

Reimplemented from Item.

◆ val_decimal()

my_decimal * Item_field::val_decimal ( my_decimal decimal_value)
overridevirtual

Implements Item.

◆ val_int()

longlong Item_field::val_int ( void  )
overridevirtual

Implements Item.

◆ val_int_endpoint()

longlong Item_field::val_int_endpoint ( bool  left_endp,
bool incl_endp 
)
overridevirtual

Reimplemented from Item.

◆ val_json()

bool Item_field::val_json ( Json_wrapper result)
overridevirtual

Get a JSON value from an Item.

All subclasses that can return a JSON value, should override this function. The function in the base class is not expected to be called. If it is called, it most likely means that some subclass is missing an override of val_json().

Parameters
[in,out]resultThe resulting Json_wrapper.
Returns
false if successful, true on failure

Reimplemented from Item.

◆ val_real()

double Item_field::val_real ( void  )
overridevirtual

Implements Item.

◆ val_str()

String * Item_field::val_str ( String str)
overridevirtual

Implements Item.

◆ val_time_temporal()

longlong Item_field::val_time_temporal ( )
overridevirtual

Return time value of item in packed longlong format.

Reimplemented from Item.

Friends And Related Function Documentation

◆ Item_default_value

friend class Item_default_value
friend

◆ Item_insert_value

friend class Item_insert_value
friend

◆ SELECT_LEX_UNIT

friend class SELECT_LEX_UNIT
friend

Member Data Documentation

◆ any_privileges

bool Item_field::any_privileges

◆ can_use_prefix_key

bool Item_field::can_use_prefix_key {false}

◆ field

Field* Item_field::field

Source field.

◆ have_privileges

uint Item_field::have_privileges

◆ item_equal

Item_equal* Item_field::item_equal

◆ no_const_subst

bool Item_field::no_const_subst

◆ orig_field

Field* Item_field::orig_field

Item's original field.

Used to compare fields in Item_field::eq() in order to get proper result when field is transformed by tmp table.

◆ result_field

Field* Item_field::result_field

Result field.

◆ table_ref

TABLE_LIST* Item_field::table_ref

Table containing this resolved field.

This is required e.g for calculation of table map. Notice that for the following types of "tables", no TABLE_LIST object is assigned and hence table_ref is NULL:

  • Temporary tables assigned by join optimizer for sorting and aggregation.
  • Stored procedure dummy tables. For fields referencing such tables, table number is always 0, and other uses of table_ref is not needed.

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