用Merge代替复杂的Update

merge into dw_cmcc_split_detail_t a using (
      select t.id,
       t.cp_id,
       t.cp_name
       from inf_cmcc_split_t t,dw_cmcc_split_detail_t t1
) ng on (ng.id=a.id)
when matched then update set a.cp_id=ng.cp_id,a.cp_name=ng.cp_name
where a.business_date='20120101'