BUG#18405221: SHOW CREATE VIEW OUTPUT INCORRECT

Fix:
---
The issue reported is same as the BUG#14117018.
Hence backporting the patch from mysql-trunk
to mysql-5.5 and mysql-5.6

1 files changed, 46 insertions, 14 deletions

diff --git a/sql/sql_view.cc b/sql/sql_view.cc
index 4a10c397508..6bbc475565b 100644
--- a/sql/sql_view.cc
+++ b/sql/sql_view.cc
@@ -1,4 +1,4 @@
-/* Copyright (c) 2004, 2013, Oracle and/or its affiliates. All rights reserved.
+/* Copyright (c) 2004, 2014, Oracle and/or its affiliates. All rights reserved.
 
    This program is free software; you can redistribute it and/or modify
    it under the terms of the GNU General Public License as published by
@@ -163,27 +163,61 @@ err:
   Check if auto generated column names are conforming and
   possibly generate a conforming name for them if not.
 
-  @param item_list  List of Items which should be checked
+  @param lex  Lex for this thread.
+
+  @retval false Operation was a success.
+  @retval true  An error occurred.
 */
 
-static void make_valid_column_names(List<Item> &item_list)
+static bool make_valid_column_names(LEX *lex)
 {
   Item *item;
   uint name_len;
-  List_iterator_fast<Item> it(item_list);
   char buff[NAME_LEN];
+  uint column_no= 1;
   DBUG_ENTER("make_valid_column_names");
 
-  for (uint column_no= 1; (item= it++); column_no++)
+  for (SELECT_LEX *sl= &lex->select_lex; sl; sl= sl->next_select())
   {
-    if (!item->is_autogenerated_name || !check_column_name(item->name))
-      continue;
-    name_len= my_snprintf(buff, NAME_LEN, "Name_exp_%u", column_no);
-    item->orig_name= item->name;
-    item->set_name(buff, name_len, system_charset_info);
+    for (List_iterator_fast<Item> it(sl->item_list); (item= it++); column_no++)
+    {
+      if (!item->is_autogenerated_name || !check_column_name(item->name))
+        continue;
+      name_len= my_snprintf(buff, NAME_LEN, "Name_exp_%u", column_no);
+      item->orig_name= item->name;
+      item->set_name(buff, name_len, system_charset_info);
+    }
+
+    /*
+      There is a possibility of generating same name for column in more than
+      one SELECT_LEX. For Example:
+
+       CREATE TABLE t1 (Name_exp_1 INT, Name_exp_2 INT, Name_exp_3 INT);
+       CREATE TABLE t2 (Name_exp_1 INT, Name_exp_2 INT, Name_exp_3 INT);
+
+       CREATE VIEW v1 AS SELECT '', t1.Name_exp_2 AS Name_exp_2 FROM t1
+                         UNION
+                         SELECT '', t2.Name_exp_1 AS Name_exp_1 from t2;
+
+      But, column names of the first SELECT_LEX is considered
+      for the output.
+
+        mysql> SELECT * FROM v1;
+        +------------+------------+
+        | Name_exp_1 | Name_exp_2 |
+        +------------+------------+
+        |            |          2 |
+        |            |          3 |
+        +------------+------------+
+
+      So, checking for duplicate names in only "sl", current
+      SELECT_LEX.
+    */
+    if (check_duplicate_names(sl->item_list, 1))
+      DBUG_RETURN(true);
   }
 
-  DBUG_VOID_RETURN;
+  DBUG_RETURN(false);
 }
 
 
@@ -590,9 +624,7 @@ bool mysql_create_view(THD *thd, TABLE_LIST *views,
   }
 
   /* Check if the auto generated column names are conforming. */
-  make_valid_column_names(select_lex->item_list);
-
-  if (check_duplicate_names(select_lex->item_list, 1))
+  if (make_valid_column_names(lex))
   {
     res= TRUE;
     goto err;