Item_null Class Reference

Inheritance diagram for Item_null:

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 ()
String *	val_str (String *str)
my_decimal *	val_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
Item *	clone_item ()
bool	is_null ()
virtual void	print (String *str, enum_query_type query_type)
Item *	safe_charset_converter (const CHARSET_INFO *tocs)
bool	check_partition_func_processor (uchar *int_arg)

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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:

mysql_register_view().

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.

Parameters:

field

Field where we want to store NULL

Return values:

0	ok
1	Field 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.

Parameters:

field

Field where we want to store NULL

Return values:

0	OK
1	Field 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.

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

• item.h
• item.cc