Fix bug#11298 insert into select from VIEW produces incorrect result

  when using ORDER BY

Insert were inserting data from last record fetched instead of inserting from 
temporary table.

Make Item_ref to save data from result_field if it's available rather then
from *ref on save_in_field() call.

mysql-test/r/view.result

@@ -1757,3 +1757,17 @@ select * from v1;
 cast(1 as decimal)
 1.00
 drop view v1;
+create table t1(f1 int);
+create table t2(f2 int);
+insert into t1 values(1),(2),(3);
+insert into t2 values(1),(2),(3);
+create view v1 as select * from t1,t2 where f1=f2;
+create table t3 (f1 int, f2 int);
+insert into t3 select * from v1 order by 1;
+select * from t3;
+f1	f2
+1	1
+2	2
+3	3
+drop view v1;
+drop table t1,t2,t3;

mysql-test/t/view.test

@@ -1599,3 +1599,16 @@ drop table t1;
 create view v1 as select cast(1 as decimal);
 select * from v1;
 drop view v1;
+#
+# Bug#11298 insert into select from VIEW produces incorrect result when 
+#           using ORDER BY
+create table t1(f1 int);
+create table t2(f2 int);
+insert into t1 values(1),(2),(3);
+insert into t2 values(1),(2),(3);
+create view v1 as select * from t1,t2 where f1=f2;
+create table t3 (f1 int, f2 int);
+insert into t3 select * from v1 order by 1;
+select * from t3;
+drop view v1;
+drop table t1,t2,t3;

sql/item.cc

@@ -4360,6 +4360,28 @@ my_decimal *Item_ref::val_decimal(my_decimal *decimal_value)
   return val;
 }
 
+int Item_ref::save_in_field(Field *to, bool no_conversions)
+{
+  int res;
+  if(result_field){
+    if (result_field->is_null())
+    {
+      null_value= 1;
+      return set_field_to_null_with_conversions(to, no_conversions);
+    }
+    else
+    {
+      to->set_notnull();
+      field_conv(to, result_field);
+      null_value= 0;
+    }
+    return 0;
+  }
+  res= (*ref)->save_in_field(to, no_conversions);
+  null_value= (*ref)->null_value;
+  return res;
+}
+
 
 void Item_ref_null_helper::print(String *str)
 {

sql/item.h

@@ -1343,8 +1343,7 @@ public:
   bool send(Protocol *prot, String *tmp);
   void make_field(Send_field *field)	{ (*ref)->make_field(field); }
   bool fix_fields(THD *, struct st_table_list *, Item **);
-  int save_in_field(Field *field, bool no_conversions)
-  { return (*ref)->save_in_field(field, no_conversions); }
+  int save_in_field(Field *field, bool no_conversions);
   void save_org_in_field(Field *field)	{ (*ref)->save_org_in_field(field); }
   enum Item_result result_type () const { return (*ref)->result_type(); }
   enum_field_types field_type() const   { return (*ref)->field_type(); }