update

update company_reg  set company_reg.hangye=Hangye.hid,no1=''
from Hangye
where  cno in
(select a.cno from company_reg a inner join company_login b on a.cno=b.cno
where pwd='****' and len(no1)>2)
and company_reg.no1 like Hangye.hname+'%'