Inheritance diagram for Item_func_group_concat:

Public Member Functions
	Item_func_group_concat (Name_resolution_context context_arg, bool is_distinct, List< Item > is_select, const SQL_I_List< ORDER > &is_order, String *is_separator)
	Item_func_group_concat (THD thd, Item_func_group_concat item)
void	cleanup ()
enum Sumfunctype	sum_func () const
const char *	func_name () const
virtual Item_result	result_type () const
virtual Field *	make_string_field (TABLE *table)
enum_field_types	field_type () const
void	clear ()
bool	add ()
void	reset_field ()
void	update_field ()
bool	fix_fields (THD , Item *)
bool	setup (THD *thd)
void	make_unique ()
double	val_real ()
longlong	val_int ()
my_decimal *	val_decimal (my_decimal *decimal_value)
bool	get_date (MYSQL_TIME *ltime, uint fuzzydate)
bool	get_time (MYSQL_TIME *ltime)
String *	val_str (String *str)
Item *	copy_or_same (THD *thd)
void	no_rows_in_result ()
virtual void	print (String *str, enum_query_type query_type)
virtual bool	change_context_processor (uchar *cntx)
Friends
int	group_concat_key_cmp_with_distinct (const void arg, const void key1, const void *key2)
int	group_concat_key_cmp_with_order (const void arg, const void key1, const void *key2)
int	dump_leaf_key (void key_arg, element_count count __attribute__((unused)), void item_arg)

Constructor & Destructor Documentation

Item_func_group_concat::Item_func_group_concat	(	Name_resolution_context *	context_arg,
		bool	distinct_arg,
		List< Item > *	select_list,
		const SQL_I_List< ORDER > &	order_list,
		String *	separator_arg
	)

Constructor of Item_func_group_concat.

Parameters:

distinct_arg	distinct
select_list	list of expression for show values
order_list	list of sort columns
separator_arg	string value of separator.

Member Function Documentation

Field * Item_func_group_concat::make_string_field ( TABLE * table ) [virtual]

Create a field to hold a string value from an item.

If max_length > CONVERT_IF_BIGGER_TO_BLOB create a blob
If max_length > 0 create a varchar
If max_length == 0 create a CHAR(0) (or VARCHAR(0) if we are grouping)

Parameters:

table Table for which the field is created

Reimplemented from Item.

void Item_func_group_concat::no_rows_in_result ( ) [inline, virtual]

Mark an aggregate as having no rows.

This function is called by the execution engine to assign 'NO ROWS FOUND' value to an aggregate item, when the underlying result set has no rows. Such value, in a general case, may be different from the default value of the item after 'clear()': e.g. a numeric item may be initialized to 0 by clear() and to NULL by no_rows_in_result().

Reimplemented from Item_sum.

void Item_func_group_concat::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_sum.

bool Item_func_group_concat::setup ( THD * thd ) [virtual]

Initialize blob_storage if GROUP_CONCAT is used with ORDER BY | DISTINCT and BLOB field count > 0.

Reimplemented from Item_sum.

Friends And Related Function Documentation

int dump_leaf_key	(	void *	key_arg,
		element_count count	__attribute__(unused),
		void *	item_arg
	)		`[friend]`

Append data from current leaf to item->result.

To avoid duplicated warnings in Item_func_group_concat::val_str()

int group_concat_key_cmp_with_distinct	(	const void *	arg,
		const void *	key1,
		const void *	key2
	)		`[friend]`

Compares the values for fields in expr list of GROUP_CONCAT.

Note:

GROUP_CONCAT([DISTINCT] expr [,expr ...] [ORDER BY {unsigned_integer | col_name | expr} [ASC | DESC] [,col_name ...]] [SEPARATOR str_val])

Returns:

Return values:

-1	: key1 < key2
0	: key1 = key2
1	: key1 > key2

int group_concat_key_cmp_with_order	(	const void *	arg,
		const void *	key1,
		const void *	key2
	)		`[friend]`

function of sort for syntax: GROUP_CONCAT(expr,... ORDER BY col,... )

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

Public Member Functions

Friends

Constructor & Destructor Documentation

Member Function Documentation

Friends And Related Function Documentation