标签：oracle update sql优化 update优化
改前:
A1
update gls_voucher t
set t.promptval = (select sum(m.originalval)
from gls_vchitem m
where m.vid = t.vid
and m.dir = 1)
;
B1
update gls_voucher t
set t.promptexplain = (select max(n.explain)
from gls_vchitem n
where n.vid = t.vid
and n.viid =
(select min(m.viid)
from gls_vchitem m
where m.vid = n.vid
and m.explain is not null))
;
改后:
A1‘
update (select n.yr, n.promptval, a.originalval newVal
from gls_voucher n
inner join (select m.vid, sum(m.originalval) originalval
from gls_vchitem m
where m.dir = 1
group by m.vid) a on n.vid = a.vid) t
set t.promptval = t.newVal
;
B1‘
update (select n.yr, n.promptexplain, q.explain newExplain
from gls_voucher n
inner join (select p.vid, max(p.explain) explain
from gls_vchitem p
inner join (select m.vid, min(m.viid) viid
from gls_vchitem m
where m.explain is not null
group by m.vid) a on p.viid = a.viid
group by p.vid) q on n.vid = q.vid) t
set t.promptexplain = t.newExplain
;
--下边这个语句会报错 ORA-01779:
无法修改与非键值保存表对应的列
说明: gls_voucher凭证(vid主键) 与 gls_vchitem凭证项(viid主键) 通过 vid
关联
目的: 更新凭证promptexplain=该凭证下凭证项中的第一条explain不为空的explain值
原因: 通过第二个inner join关联后,oracle不能确定gls_voucher
n和gls_vchitem p是一对一的查询,改成上面B1‘就行了
update (select n.yr, n.promptexplain, p.explain newExplain
from gls_voucher n
inner join (select m.vid, min(m.viid) viid
from gls_vchitem m
where m.explain is not null
group by m.vid) a on n.vid = a.vid
inner join gls_vchitem p on a.viid = p.viid) t
set t.promptexplain = t.newExplain
优化update-虚拟表
标签：oracle update sql优化 update优化
原文地址：http://blog.csdn.net/cxx504659987/article/details/44829901
