Added the error ER_WRONG_TYPE_FOR_PERCENTILE_CONT, which ensures that…

… the result type for percentile_cont is always numerical

sql/item_windowfunc.cc

@@ -178,25 +178,24 @@ void Item_window_func::split_sum_func(THD *thd, Ref_ptr_array ref_pointer_array,
   window_func()->setup_caches(thd);
 }
 
-bool Item_window_func::check_order_list()
+bool Item_window_func::check_result_type_of_order_item()
 {
   if (only_single_element_order_list())
   {
     Item_result rtype= window_spec->order_list->first->item[0]->result_type();
     if (rtype != REAL_RESULT && rtype != INT_RESULT &&
-        rtype != DECIMAL_RESULT)
+        rtype != DECIMAL_RESULT && window_func()->sum_func() == Item_sum::PERCENTILE_CONT_FUNC)
     {
-      // TODO(varun) please change the error name
-      my_error(ER_WRONG_TYPE_FOR_RANGE_FRAME, MYF(0),"percentile functions");
+      my_error(ER_WRONG_TYPE_FOR_PERCENTILE_CONT, MYF(0));
       return TRUE;
     }
+    setting_handler_for_percentile_functions(rtype);
   }
   return FALSE;
 }
 
 /*
   This must be called before attempting to compute the window function values.
-
   @detail
     If we attempt to do it in fix_fields(), partition_fields will refer
     to the original window function arguments.
@@ -222,7 +221,6 @@ void Item_sum_dense_rank::setup_window_func(THD *thd, Window_spec *window_spec)
 void Item_sum_percentile_disc::setup_window_func(THD *thd, Window_spec *window_spec)
 {
   order_item= window_spec->order_list->first->item[0];
-  set_handler_by_cmp_type(order_item->result_type());
   if (!(value= order_item->get_cache(thd)))
     return;
   value->setup(thd, order_item);
@@ -235,7 +233,6 @@ void Item_sum_percentile_cont::setup_window_func(THD *thd, Window_spec *window_s
   /* TODO(varun): need to discuss and finalise what type should we
      return for percentile cont functions
   */
-  //set_handler_by_cmp_type(order_item->result_type());
   if (!(ceil_value= order_item->get_cache(thd)))
     return;
   ceil_value->setup(thd, order_item);