fixed union types merging and table related metadata (BUG#8824)

mysql-test/r/func_group.result:
  new result
mysql-test/r/metadata.result:
  new result
  test of metadata of variables, unions and derived tables
mysql-test/r/union.result:
  new results
  test of union of enum
mysql-test/t/metadata.test:
  test of metadata of variables, unions and derived tables
mysql-test/t/union.test:
  test of union of enum
sql/field.cc:
  Field type merging rules added
  Fixed table name/alias returting for field made from temporary tables
sql/field.h:
  removed unned field type reporting
sql/item.cc:
  fixed bug in NEW_DATE type field creartion
  replaced mechanism of merging types of UNION
sql/item.h:
  replaced mechanism of merging types of UNION
sql/item_func.h:
  new item type to make correct field type detection possible
sql/item_subselect.cc:
  added table name parameter to prepare() to show right table alias for derived tables
sql/sql_derived.cc:
  added table name parameter to prepare() to show right table alias for derived tables
sql/sql_lex.h:
  added table name parameter to prepare() to show right table alias for derived tables
sql/sql_parse.cc:
  made function for enum/set pack length calculation
sql/sql_prepare.cc:
  added table name parameter to prepare() to show right table alias for derived tables
sql/sql_select.cc:
  new temporary table field creation by Item_type_holder
  fixed table alias for temporary table
sql/sql_union.cc:
  added table name parameter to prepare() to show right table alias for derived tables

1 files changed, 2 insertions, 1 deletions

diff --git a/sql/item_func.h b/sql/item_func.h
index 2738c7419ca..7cd82dc7c10 100644
--- a/sql/item_func.h
+++ b/sql/item_func.h
@@ -51,7 +51,7 @@ public:
 		  SP_CONTAINS_FUNC,SP_OVERLAPS_FUNC,
 		  SP_STARTPOINT,SP_ENDPOINT,SP_EXTERIORRING,
 		  SP_POINTN,SP_GEOMETRYN,SP_INTERIORRINGN,
-		  NOT_FUNC, NOT_ALL_FUNC, NOW_FUNC};
+		  NOT_FUNC, NOT_ALL_FUNC, NOW_FUNC, VAR_VALUE_FUNC};
   enum optimize_type { OPTIMIZE_NONE,OPTIMIZE_KEY,OPTIMIZE_OP, OPTIMIZE_NULL };
   enum Type type() const { return FUNC_ITEM; }
   virtual enum Functype functype() const   { return UNKNOWN_FUNC; }
@@ -980,6 +980,7 @@ public:
     select @t1:=1,@t1,@t:="hello",@t from foo where (@t1:= t2.b)
   */
   enum_field_types field_type() const  { return MYSQL_TYPE_STRING; }
+  enum Functype functype() const   { return VAR_VALUE_FUNC; }
   const char *func_name() const { return "get_user_var"; }
   bool const_item() const;
   table_map used_tables() const