fixed view fields names check and generation (changed after Trudy review: underlying field names treat as user set ones) (BUG#7448)

1 files changed, 71 insertions, 4 deletions

diff --git a/sql/sql_view.cc b/sql/sql_view.cc
index 5152619fd85..0b351407c13 100644
--- a/sql/sql_view.cc
+++ b/sql/sql_view.cc
@@ -36,6 +36,61 @@ TYPELIB updatable_views_with_limit_typelib=
 
 
 /*
+  Make a unique name for an anonymous view column
+  SYNOPSIS
+    target        reference to the item for which a new name has to be made
+    item_list     list of items within which we should check uniqueness of
+                  the created name
+    last_element  the last element of the list above
+
+  NOTE
+    Unique names are generated by adding 'My_exp_' to the old name of the
+    column. In case the name that was created this way already exists, we
+    add a numeric postfix to its end (i.e. "1") and increase the number
+    until the name becomes unique. If the generated name is longer than
+    NAME_LEN, it is truncated.
+*/
+
+static void make_unique_view_field_name(Item *target,
+                                        List<Item> &item_list,
+                                        Item *last_element)
+{
+  char *name= (target->orig_name ?
+               target->orig_name :
+               target->name);
+  uint name_len;
+  uint attempt= 0;
+  char buff[NAME_LEN+1];
+  for (;; attempt++)
+  {
+    Item *check;
+    List_iterator_fast<Item> itc(item_list);
+    bool ok= TRUE;
+
+    if (attempt)
+      name_len= my_snprintf(buff, NAME_LEN, "My_exp_%d_%s", attempt, name);
+    else
+      name_len= my_snprintf(buff, NAME_LEN, "My_exp_%s", name);
+
+    do
+    {
+      check= itc++;
+      if (check != target &&
+          my_strcasecmp(system_charset_info, buff, check->name) == 0)
+      {
+        ok= FALSE;
+        break;
+      }
+    } while (check != last_element);
+    if (ok)
+      break;
+  }
+
+  target->orig_name= target->name;
+  target->set_name(buff, name_len, system_charset_info);
+}
+
+/*
   Creating/altering VIEW procedure
 
   SYNOPSIS
@@ -240,24 +295,36 @@ bool mysql_create_view(THD *thd,
       goto err;
     }
     while ((item= it++, name= nm++))
+    {
       item->set_name(name->str, name->length, system_charset_info);
+      item->is_autogenerated_name= FALSE;
+    }
   }
 
   /* Test absence of duplicates names */
   {
     Item *item;
     List_iterator_fast<Item> it(select_lex->item_list);
-    it++;
     while ((item= it++))
     {
       Item *check;
       List_iterator_fast<Item> itc(select_lex->item_list);
+      /* treat underlying fields like set by user names */
+      if (item->real_item()->type() == Item::FIELD_ITEM)
+        item->is_autogenerated_name= FALSE;
       while ((check= itc++) && check != item)
       {
-        if (strcmp(item->name, check->name) == 0)
+        if (my_strcasecmp(system_charset_info, item->name, check->name) == 0)
         {
-          my_error(ER_DUP_FIELDNAME, MYF(0), item->name);
-          DBUG_RETURN(TRUE);
+          if (item->is_autogenerated_name)
+            make_unique_view_field_name(item, select_lex->item_list, item);
+          else if (check->is_autogenerated_name)
+            make_unique_view_field_name(check, select_lex->item_list, item);
+          else
+          {
+            my_error(ER_DUP_FIELDNAME, MYF(0), item->name);
+            DBUG_RETURN(TRUE);
+          }
         }
       }
     }