Inheritance diagram for Item_insert_value:

Public Member Functions
	Item_insert_value (Name_resolution_context context_arg, Item a)
bool	eq (const Item *item, bool binary_cmp) const
bool	fix_fields (THD , Item *)
virtual void	print (String *str, enum_query_type query_type)
type_conversion_status	save_in_field (Field *field_arg, bool no_conversions)
table_map	used_tables () const
bool	walk (Item_processor processor, bool walk_subquery, uchar *args)
Public Attributes
Item *	arg

Member Function Documentation

bool Item_insert_value::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_field.

bool Item_insert_value::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_field.

void Item_insert_value::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_field.

type_conversion_status Item_insert_value::save_in_field	(	Field *	field,
		bool	no_conversions
	)		`[inline, 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_field.

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

item.h
item.cc

Public Member Functions

Public Attributes

Member Function Documentation