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, 1 insertions, 1 deletions

diff --git a/mysql-test/r/func_group.result b/mysql-test/r/func_group.result
index c22d0d3bec8..2fb18ca92c7 100644
--- a/mysql-test/r/func_group.result
+++ b/mysql-test/r/func_group.result
@@ -747,7 +747,7 @@ insert into t1 values (now());
 create table t2 select f2 from (select max(now()) f2 from t1) a;
 show columns from t2;
 Field	Type	Null	Key	Default	Extra
-f2	datetime			0000-00-00 00:00:00	
+f2	datetime	YES		NULL	
 drop table t2;
 create table t2 select f2 from (select now() f2 from t1) a;
 show columns from t2;