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Item_null Class Reference
Inheritance diagram for Item_null:
Item_basic_constant Item Item_null_result

List of all members.

Public Member Functions

 Item_null (const Name_string &name_par)
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 ()
Stringval_str (String *str)
my_decimalval_decimal (my_decimal *)
bool get_date (MYSQL_TIME *ltime, uint fuzzydate)
bool get_time (MYSQL_TIME *ltime)
type_conversion_status save_in_field (Field *field, bool no_conversions)
type_conversion_status save_safe_in_field (Field *field)
bool send (Protocol *protocol, String *str)
enum Item_result result_type () const
enum_field_types field_type () const
bool basic_const_item () const
Itemclone_item ()
bool is_null ()
virtual void print (String *str, enum_query_type query_type)
Itemsafe_charset_converter (const CHARSET_INFO *tocs)
bool check_partition_func_processor (uchar *int_arg)

Member Function Documentation

bool Item_null::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.

virtual void Item_null::print ( String str,
enum_query_type  query_type 
) [inline, 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:

Reimplemented from Item.

type_conversion_status Item_null::save_in_field ( Field field,
bool  no_conversions 
) [virtual]

Store null in field.

This is used on INSERT. Allow NULL to be inserted in timestamp and auto_increment values.

fieldField where we want to store NULL
Return values:
1Field doesn't support NULL values and can't handle 'field = NULL'

Reimplemented from Item.

type_conversion_status Item_null::save_safe_in_field ( Field field) [virtual]

Store null in field.

fieldField where we want to store NULL
Return values:
1Field doesn't support NULL values

Reimplemented from Item.

bool Item_null::send ( Protocol protocol,
String packet 
) [virtual]

Pack data in buffer for sending.

Reimplemented from Item.

longlong Item_null::val_date_temporal ( ) [inline, virtual]

Return date value of item in packed longlong format.

Reimplemented from Item.

longlong Item_null::val_time_temporal ( ) [inline, virtual]

Return time value of item in packed longlong format.

Reimplemented from Item.

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