同时update两个列值的问题

Question

update BANKFROZENFLOW a set (a.Companycode,a.departmentid)=
(select nvl(b.Companycode,1), nvl(b.departmentid,1) from SECUACCINFO b where b.bankaccount=a.bankaccount)

Answer 1

不行，系统提示不能update companycode to null

Answer 2

update BANKFROZENFLOW a set (a.Companycode,a.departmentid)=
(select nvl(b.Companycode,1), nvl(b.departmentid,1) from SECUACCINFO b where b.bankaccount=a.bankaccount)
where exists (select 1 from SECUACCINFO b where b.bankaccount=a.bankaccount )