Final solution for bug# 4302 "Ambiguos order by when renamed column is

identical to another in result"
According to SQL standard queries like 
"select t1.a as col from t1, t2 order by a" should return an error if
both tables contain field a.


mysql-test/r/order_by.result:
  Updated test to conform SQL-standard.
mysql-test/t/order_by.test:
  Updated test to conform SQL-standard.
sql/item.cc:
  find_item_in_list() has now one more out parameter which is not used
  in item.cc functions.
sql/mysql_priv.h:
  find_item_in_list(): Added boolean out parameter "unaliased" which
  indicates that we have found field by its original name and not by
  its alias in item (select) list.
sql/sql_base.cc:
  find_item_in_list(): Added boolean out parameter "unaliased" which
  indicates that we have found field by its original name and not by
  its alias in item (select) list. This means that additional check is
  required to ensure there will be no ambiguity if we would search for this
  field in all tables.
sql/sql_select.cc:
  find_order_in_list(): If we have found field in select list by its
  original name and not by its alias then we should perform additional
  check to ensure that there will be no ambiguity if we will search for
  this field in all tables. Also small cleanup.

1 files changed, 9 insertions, 7 deletions

diff --git a/sql/item.cc b/sql/item.cc
index 14136435a50..3c9b54074dc 100644
--- a/sql/item.cc
+++ b/sql/item.cc
@@ -1246,6 +1246,7 @@ bool Item_field::fix_fields(THD *thd, TABLE_LIST *tables, Item **ref)
       TABLE_LIST *table_list;
       Item **refer= (Item **)not_found_item;
       uint counter;
+      bool not_used;
       // Prevent using outer fields in subselects, that is not supported now
       SELECT_LEX *cursel= (SELECT_LEX *) thd->lex->current_select;
       if (cursel->master_unit()->first_select()->linkage != DERIVED_TABLE_TYPE)
@@ -1288,7 +1289,8 @@ bool Item_field::fix_fields(THD *thd, TABLE_LIST *tables, Item **ref)
           }
 	  if (sl->resolve_mode == SELECT_LEX::SELECT_MODE &&
 	      (refer= find_item_in_list(this, sl->item_list, &counter,
-					 REPORT_EXCEPT_NOT_FOUND)) !=
+                                        REPORT_EXCEPT_NOT_FOUND,
+                                        &not_used)) !=
 	       (Item **) not_found_item)
 	  {
 	    if (*refer && (*refer)->fixed) // Avoid crash in case of error
@@ -1889,6 +1891,7 @@ bool Item_ref::fix_fields(THD *thd,TABLE_LIST *tables, Item **reference)
 {
   DBUG_ASSERT(fixed == 0);
   uint counter;
+  bool not_used;
   if (!ref)
   {
     TABLE_LIST *where= 0, *table_list;
@@ -1908,13 +1911,13 @@ bool Item_ref::fix_fields(THD *thd,TABLE_LIST *tables, Item **reference)
 				  first_select()->linkage !=
 				  DERIVED_TABLE_TYPE) ? 
 				  REPORT_EXCEPT_NOT_FOUND :
-				  REPORT_ALL_ERRORS))) ==
+				  REPORT_ALL_ERRORS ), &not_used)) ==
 	(Item **)not_found_item)
     {
       upward_lookup= 1;
       Field *tmp= (Field*) not_found_field;
       /*
-	We can't find table field in table list of current select,
+	We can't find table field in select list of current select,
 	consequently we have to find it in outer subselect(s).
 	We can't join lists of outer & current select, because of scope
 	of view rules. For example if both tables (outer & current) have
@@ -1929,8 +1932,8 @@ bool Item_ref::fix_fields(THD *thd,TABLE_LIST *tables, Item **reference)
 	Item_subselect *prev_subselect_item= prev_unit->item;
 	if (sl->resolve_mode == SELECT_LEX::SELECT_MODE &&
 	    (ref= find_item_in_list(this, sl->item_list,
-				    &counter,
-				    REPORT_EXCEPT_NOT_FOUND)) !=
+                                    &counter, REPORT_EXCEPT_NOT_FOUND,
+                                    &not_used)) !=
 	   (Item **)not_found_item)
 	{
 	  if (*ref && (*ref)->fixed) // Avoid crash in case of error
@@ -1989,8 +1992,7 @@ bool Item_ref::fix_fields(THD *thd,TABLE_LIST *tables, Item **reference)
 	  // Call to report error
 	  find_item_in_list(this,
 			    *(thd->lex->current_select->get_item_list()),
-			    &counter,
-			    REPORT_ALL_ERRORS);
+			    &counter, REPORT_ALL_ERRORS, &not_used);
 	}
         ref= 0;
 	return 1;