UPDATE t_detail t
   SET val = null
 WHERE t.h_h_id = (SELECT h_id FROM t_header WHERE code = '666');

UPDATE t_detail t
   SET val = null
 WHERE exists (SELECT h_id FROM t_header WHERE code = '666' and h_id = t.h_h_id);

UPDATE t_detail t
   SET val = null
 WHERE t.h_h_id = (SELECT h_id FROM t_header WHERE code = '666');

UPDATE (-- key preserned view
        SELECT t.val AS t_val 
        FROM t_detail t, t_header H
        WHERE H.h_id = t.h_h_id
          AND H.code = '666')
SET val = null;

create table tmp_parent(id int primary key, x int);
create table tmp_child(id int, parent_id int, y int);
update (select c.y from tmp_parent p, tmp_child c where p.x = 1 and c.parent_id = p.id) set y = 2;

0 rows updated.

SQL*Plus: Release 10.2.0.4.0 - Production on Mon Oct 19 21:45:54 2009
Connected to: Oracle Database 11g Enterprise Edition Release 11.1.0.6.0 - Production

SQL> create table tmp_parent(id int primary key, x int);
Table created.

SQL> create table tmp_child(id int, parent_id int, y int);
Table created.
SQL> CREATE VIEW tmp_parent_child
  2  AS
  3  select c.y from tmp_parent p, tmp_child c where p.x = 1 and c.parent_id = p.id
  4  ;
View created.

SQL> COLUMN owner FORMAT A6;
SQL> COLUMN table_name FORMAT A18;
SQL> COLUMN column_name FORMAT A12;
SQL> COLUMN INSERTABLE FORMAT A10;
SQL> COLUMN UPDATABLE FORMAT A10;
SQL> COLUMN DELETABLE FORMAT A10;

SQL> -- Первичный ключ включен UPDATABLE = YES
SQL> select * from user_updatable_columns
  2  WHERE table_name = 'TMP_PARENT_CHILD';

OWNER  TABLE_NAME         COLUMN_NAME  UPDATABLE  INSERTABLE DELETABLE
------ ------------------ ------------ ---------- ---------- ----------
SCOTT  TMP_PARENT_CHILD   Y            YES        YES        YES

SQL> -- Update выполняется без ошибок
SQL> update tmp_parent_child set y = 2;
0 rows updated.

SQL> -- ВЫключаем первичный ключ
SQL> ALTER TABLE tmp_parent DISABLE PRIMARY KEY;
Table altered.

SQL> -- Первичный ключ выключен, однако UPDATABLE всё еще YES
SQL> select * from user_updatable_columns
  2  WHERE table_name = 'TMP_PARENT_CHILD';

OWNER  TABLE_NAME         COLUMN_NAME  UPDATABLE  INSERTABLE DELETABLE
------ ------------------ ------------ ---------- ---------- ----------
SCOTT  TMP_PARENT_CHILD   Y            YES        YES        YES

SQL> -- Попытка UPDATE вызывает ошибку
SQL> -- ORA-01779: cannot modify a column which maps to a non key-preserved table
SQL> update tmp_parent_child set y = 2;
update tmp_parent_child set y = 2
                            *
ERROR at line 1:
ORA-01779: cannot modify a column which maps to a non key-preserved table

SQL> -- Теперь UPDATABLE стало NO
SQL> select * from user_updatable_columns
  2  WHERE table_name = 'TMP_PARENT_CHILD';

OWNER  TABLE_NAME         COLUMN_NAME  UPDATABLE  INSERTABLE DELETABLE
------ ------------------ ------------ ---------- ---------- ----------
SCOTT  TMP_PARENT_CHILD   Y            NO         NO         NO

SQL> -- Статус VIEW до выключения первичного ключа
SQL> SELECT object_name, object_type, status
  2  FROM user_objects
  3  WHERE object_name = 'TMP_PARENT_CHILD';

OBJECT_NAME        OBJECT_TYPE  STATUS
------------------ ------------ -------
TMP_PARENT_CHILD   VIEW         VALID

SQL> -- ВЫключаем первичный ключ
SQL> ALTER TABLE tmp_parent DISABLE PRIMARY KEY;

Table altered.

SQL> -- Статус VIEW после выключения первичного ключа
SQL> SELECT object_name, object_type, status
  2  FROM user_objects
  3  WHERE object_name = 'TMP_PARENT_CHILD';

OBJECT_NAME        OBJECT_TYPE  STATUS
------------------ ------------ -------
TMP_PARENT_CHILD   VIEW         INVALID

SQL> SELECT * FROM v$version WHERE rownum = 1;
 
BANNER
----------------------------------------------------------------
Oracle Database 10g Release 10.2.0.4.0 - 64bit Production
SQL> SELECT LEVEL, (SELECT 'hello world' FROM dual) val
  2    FROM dual
  3   START WITH 1 = (SELECT 1 id FROM dual)
  4  CONNECT BY LEVEL <= (SELECT 3 id FROM dual);
 
     LEVEL VAL
---------- -----------
         1 hello world
         2 hello world
         3 hello world