Oracle way:

```
SQL> select "created_at" from resurtm."orders" where "key1"=1;

created_at
---------------------------------------------------------------------------
09-MAR-13 12.15.13.143000 PM
09-MAR-13 12.15.13.143000 PM

SQL> update resurtm."orders" set "created_at" = now() where "key1" = 1;
update resurtm."orders" set "created_at" = now() where "key1" = 1
                                           *
ERROR at line 1:
ORA-00904: "NOW": invalid identifier


SQL> update resurtm."orders" set "created_at" = (select systimestamp from dual)
where "key1" = 1;

2 rows updated.

SQL> select "created_at" from resurtm."orders" where "key1"=1;

created_at
---------------------------------------------------------------------------
09-MAR-13 12.16.02.376000 PM
09-MAR-13 12.16.02.376000 PM

SQL> commit;

Commit complete.

SQL> select "created_at" from resurtm."orders" where "key1"=1;

created_at
---------------------------------------------------------------------------
09-MAR-13 12.16.02.376000 PM
09-MAR-13 12.16.02.376000 PM

SQL>
```