本文介绍了在Oracle数据库中执行更新操作时如何使用带有EXISTS子句的WHERE条件来提高效率和准确性。通过具体示例展示了如何在UPDATE语句中应用这种技术。
oracle中update时要注意加where exists判断，如：
update
sysmanage.tmp_p8030009 a
set
a.today_stockvalue
=
(
select
ta.stockvalue_rmb
from
(
select
account_id,
sum
(stockvalue_rmb)
as
stockvalue_rmb
from
olap.tb_inn_stk_bal_cur_month
where
occur_date
=
i_startdate
group
by
account_id ) ta
where
ta.account_id
=
a.account_id)
where
exists
(
select
1
from
(
select
account_id,
sum
(stockvalue_rmb)
as
stockvalue_rmb
from
olap.tb_inn_stk_bal_cur_month
where
occur_date
=
i_startdate
group
by
account_id ) ta
where
ta.account_id
=
a.account_id);
或者把exists条件改为in都可以，
where
a.account_id
in
(...).
update
sysmanage.tmp_p8030009 a
set
a.today_stockvalue
=
(
select
ta.stockvalue_rmb
from
(
select
account_id,
sum
(stockvalue_rmb)
as
stockvalue_rmb
from
olap.tb_inn_stk_bal_cur_month
where
occur_date
=
i_startdate
group
by
account_id ) ta
where
ta.account_id
=
a.account_id)
where
exists
(
select
1
from
(
select
account_id,
sum
(stockvalue_rmb)
as
stockvalue_rmb
from
olap.tb_inn_stk_bal_cur_month
where
occur_date
=
i_startdate
group
by
account_id ) ta
where
ta.account_id
=
a.account_id);或者把exists条件改为in都可以，
where
a.account_id
in
(...).
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