/** XXX CODING HORROR... */
必要に応じて、更新可能なビューを使用できます。 。ベーステーブルのビューを作成し、このビューに「代わりに」トリガーを追加して、ビューを直接更新します。
いくつかのテーブルの例:
create table party (
party_id integer,
employee_id integer
);
create table party_name (
party_id integer,
first_name varchar2(120 char),
last_name varchar2(120 char)
);
insert into party values (1,1000);
insert into party values (2,2000);
insert into party values (3,3000);
insert into party_name values (1,'Kipper','Family');
insert into party_name values (2,'Biff','Family');
insert into party_name values (3,'Chip','Family');
commit;
select * from party_v;
PARTY_ID EMPLOYEE_ID FIRST_NAME LAST_NAME
1 1000 Kipper Family
2 2000 Biff Family
3 3000 Chip Family
...次に更新可能なビューを作成します
create or replace view party_v
as
select
p.party_id,
p.employee_id,
n.first_name,
n.last_name
from
party p left join party_name n on p.party_id = n.party_id;
create or replace trigger trg_party_update
instead of update on party_v
for each row
declare
begin
--
update party
set
party_id = :new.party_id,
employee_id = :new.employee_id
where
party_id = :old.party_id;
--
update party_name
set
party_id = :new.party_id,
first_name = :new.first_name,
last_name = :new.last_name
where
party_id = :old.party_id;
--
end;
/
ビューを直接更新できるようになりました...
update party_v
set
employee_id = 42,
last_name = 'Oxford'
where
party_id = 1;
select * from party_v;
PARTY_ID EMPLOYEE_ID FIRST_NAME LAST_NAME
1 42 Kipper Oxford
2 2000 Biff Family
3 3000 Chip Family