fixed problem with groupping by view (BUG#7116)

mysql-test/r/view.result:
  view and group_concat()
mysql-test/t/view.test:
  view and group_concat()
sql/item.cc:
  comments added
sql/sql_select.cc:
  fixed ORDER/GROUP BY processing for view support

mysql-test/r/view.result

@@ -1758,3 +1758,16 @@ SELECT * FROM v2;
 C1
 drop view v2, v1;
 drop table t1, t2;
+create table t1 (col1 char(5),col2 int,col3 int);
+insert into t1 values ('one',10,25), ('two',10,50), ('two',10,50), ('one',20,25), ('one',30,25);
+create view v1 as select * from t1;
+select col1,group_concat(col2,col3) from t1 group by col1;
+col1	group_concat(col2,col3)
+one	1025,2025,3025
+two	1050,1050
+select col1,group_concat(col2,col3) from v1 group by col1;
+col1	group_concat(col2,col3)
+two	1025,2025,3025
+two	1050,1050
+drop view v1;
+drop table t1;

mysql-test/t/view.test

@@ -1690,3 +1690,14 @@ CREATE VIEW v2 AS SELECT C1 FROM t1 LEFT OUTER JOIN v1 USING (C2);
 SELECT * FROM v2;
 drop view v2, v1;
 drop table t1, t2;
+
+#
+# view and group_concat() (BUG#7116)
+#
+create table t1 (col1 char(5),col2 int,col3 int); 
+insert into t1 values ('one',10,25), ('two',10,50), ('two',10,50), ('one',20,25), ('one',30,25); 
+create view v1 as select * from t1;
+select col1,group_concat(col2,col3) from t1 group by col1;
+select col1,group_concat(col2,col3) from v1 group by col1;
+drop view v1;
+drop table t1;

sql/item.cc

@@ -1853,6 +1853,11 @@ bool Item_field::fix_fields(THD *thd, TABLE_LIST *tables, Item **reference)
   {
     bool upward_lookup= FALSE;
     Field *from_field= (Field *)not_found_field;
+    /*
+      In case of view, find_field_in_tables() write pointer to view field
+      expression to 'reference', i.e. it substitute that expression instead
+      of this Item_field
+    */
     if ((from_field= find_field_in_tables(thd, this, tables, reference,
                                    IGNORE_EXCEPT_NON_UNIQUE,
                                    !any_privileges)) ==
@@ -1898,6 +1903,10 @@ bool Item_field::fix_fields(THD *thd, TABLE_LIST *tables, Item **reference)
             Check table fields only if the subquery is used somewhere out of
             HAVING, or the outer SELECT does not use grouping (i.e. tables are
             accessible).
+
+            In case of view, find_field_in_tables() write pointer to view
+            field expression to 'reference', i.e. it substitute that
+            expression instead of this Item_field
           */
           if ((place != IN_HAVING ||
                (outer_sel->with_sum_func == 0 &&
@@ -2951,6 +2960,11 @@ bool Item_ref::fix_fields(THD *thd, TABLE_LIST *tables, Item **reference)
                (!outer_sel->with_sum_func &&
                 outer_sel->group_list.elements == 0)))
           {
+            /*
+              In case of view, find_field_in_tables() write pointer to view
+              field expression to 'reference', i.e. it substitute that
+              expression instead of this Item_ref
+            */
             if ((from_field= find_field_in_tables(thd, this, table_list,
                                                   reference,
                                                   IGNORE_EXCEPT_NON_UNIQUE,

sql/sql_select.cc

@@ -11351,22 +11351,24 @@ find_order_in_list(THD *thd, Item **ref_pointer_array, TABLE_LIST *tables,
   /* Check whether the resolved field is not ambiguos. */
   if (select_item != not_found_item)
   {
+    Item *view_ref= NULL;
     /*
       If we have found field not by its alias in select list but by its
       original field name, we should additionaly check if we have conflict
       for this name (in case if we would perform lookup in all tables).
     */
-    if (unaliased && !order_item->fixed && order_item->fix_fields(thd, tables, order->item))
+    if (unaliased && !order_item->fixed && order_item->fix_fields(thd, tables,
+                                                                  order->item))
       return 1;
 
     /* Lookup the current GROUP field in the FROM clause. */
     order_item_type= order_item->type();
     if (is_group_field &&
-        order_item_type == Item::FIELD_ITEM || order_item_type == Item::REF_ITEM)
+        order_item_type == Item::FIELD_ITEM ||
+        order_item_type == Item::REF_ITEM)
     {
-      Item **view_ref= NULL;
       from_field= find_field_in_tables(thd, (Item_ident*) order_item, tables,
-                                       view_ref, IGNORE_ERRORS, TRUE);
+                                       &view_ref, IGNORE_ERRORS, TRUE);
       if(!from_field)
        from_field= (Field*) not_found_field;
     }
@@ -11374,9 +11376,19 @@ find_order_in_list(THD *thd, Item **ref_pointer_array, TABLE_LIST *tables,
       from_field= (Field*) not_found_field;
 
     if (from_field == not_found_field ||
-        from_field && from_field != view_ref_found &&
-        (*select_item)->type() == Item::FIELD_ITEM &&
-        ((Item_field*) (*select_item))->field->eq(from_field))
+        from_field &&
+        (from_field != view_ref_found ?
+         /* it is field of base table => check that fields are same */
+         ((*select_item)->type() == Item::FIELD_ITEM &&
+          ((Item_field*) (*select_item))->field->eq(from_field)) :
+         /*
+           in is field of view table => check that references on translation
+           table are same
+         */
+         ((*select_item)->type() == Item::Item::REF_ITEM &&
+          view_ref->type() == Item::Item::REF_ITEM &&
+          ((Item_ref *) (*select_item))->ref ==
+          ((Item_ref *) view_ref)->ref)))
       /*
         If there is no such field in the FROM clause, or it is the same field as
         the one found in the SELECT clause, then use the Item created for the