1 files changed, 44 insertions, 30 deletions

diff --git a/sql/item.cc b/sql/item.cc
index 47635b14f46..08599f1d486 100644
--- a/sql/item.cc
+++ b/sql/item.cc
@@ -4381,8 +4381,6 @@ static Item** find_field_in_group_list(Item *find_item, ORDER *group_list)
   const char *field_name;
   ORDER      *found_group= NULL;
   int         found_match_degree= 0;
-  Item_ident *cur_field;
-  int         cur_match_degree= 0;
   char        name_buff[SAFE_NAME_LEN+1];
 
   if (find_item->type() == Item::FIELD_ITEM ||
@@ -4407,54 +4405,70 @@ static Item** find_field_in_group_list(Item *find_item, ORDER *group_list)
 
   for (ORDER *cur_group= group_list ; cur_group ; cur_group= cur_group->next)
   {
-    if ((*(cur_group->item))->real_item()->type() == Item::FIELD_ITEM)
+    int cur_match_degree= 0;
+
+    /* SELECT list element with explicit alias */
+    if ((*(cur_group->item))->name &&
+        !(*(cur_group->item))->is_autogenerated_name &&
+        !my_strcasecmp(system_charset_info,
+                       (*(cur_group->item))->name, field_name))
+    {
+      ++cur_match_degree;
+    }
+    /* Reference on the field or view/derived field. */
+    else if ((*(cur_group->item))->type() == Item::FIELD_ITEM ||
+             (*(cur_group->item))->type() == Item::REF_ITEM )
     {
-      cur_field= (Item_ident*) *cur_group->item;
-      cur_match_degree= 0;
-      
-      DBUG_ASSERT(cur_field->field_name != 0);
+      Item_ident *cur_field= (Item_ident*) *cur_group->item;
+      const char *l_db_name= cur_field->db_name;
+      const char *l_table_name= cur_field->table_name;
+      const char *l_field_name= cur_field->field_name;
+
+      DBUG_ASSERT(l_field_name != 0);
 
       if (!my_strcasecmp(system_charset_info,
-                         cur_field->field_name, field_name))
+                         l_field_name, field_name))
         ++cur_match_degree;
       else
         continue;
 
-      if (cur_field->table_name && table_name)
+      if (l_table_name && table_name)
       {
         /* If field_name is qualified by a table name. */
-        if (my_strcasecmp(table_alias_charset, cur_field->table_name, table_name))
+        if (my_strcasecmp(table_alias_charset, l_table_name, table_name))
           /* Same field names, different tables. */
           return NULL;
 
         ++cur_match_degree;
-        if (cur_field->db_name && db_name)
+        if (l_db_name && db_name)
         {
           /* If field_name is also qualified by a database name. */
-          if (strcmp(cur_field->db_name, db_name))
+          if (strcmp(l_db_name, db_name))
             /* Same field names, different databases. */
             return NULL;
           ++cur_match_degree;
         }
       }
+    }
+    else
+      continue;
 
-      if (cur_match_degree > found_match_degree)
-      {
-        found_match_degree= cur_match_degree;
-        found_group= cur_group;
-      }
-      else if (found_group && (cur_match_degree == found_match_degree) &&
-               ! (*(found_group->item))->eq(cur_field, 0))
-      {
-        /*
-          If the current resolve candidate matches equally well as the current
-          best match, they must reference the same column, otherwise the field
-          is ambiguous.
-        */
-        my_error(ER_NON_UNIQ_ERROR, MYF(0),
-                 find_item->full_name(), current_thd->where);
-        return NULL;
-      }
+    if (cur_match_degree > found_match_degree)
+    {
+      found_match_degree= cur_match_degree;
+      found_group= cur_group;
+    }
+    else if (found_group && (cur_match_degree == found_match_degree) &&
+             !(*(found_group->item))->eq((*(cur_group->item)), 0))
+    {
+      /*
+        If the current resolve candidate matches equally well as the current
+        best match, they must reference the same column, otherwise the field
+        is ambiguous.
+      */
+      my_error(ER_NON_UNIQ_ERROR, MYF(0),
+               find_item->full_name(), current_thd->where);
+      return NULL;
     }
   }
 
@@ -5509,6 +5523,7 @@ String *Item::check_well_formed_result(String *str, bool send_error)
   /* Check whether we got a well-formed string */
   CHARSET_INFO *cs= str->charset();
   uint wlen= str->well_formed_length();
+  null_value= false;
   if (wlen < str->length())
   {
     THD *thd= current_thd;
@@ -9850,4 +9865,3 @@ const char *dbug_print_item(Item *item)
 }
 
 #endif /*DBUG_OFF*/
-