关于游标优化

Question

游标查询语句中没有条件? 那就可以不这么写了. 直接update....避免 :)
在update的子查询需要用多少时间呢? 大概有多少条记录呢?

Answer 1

dm_depot 表北遍历了两次，2万条记录就不是2万了，
可以调试一下永别的方法来替代，

Answer 2

begin
  update dm_depot t
     set t.status = (select bill_type
                       from (select bill_type
                               from tmp_depot_bill
                              where project_no = t.project_no and
                                    product_name = t.product_name and
                                    year_no = t.year_no and
                                    batch_no = t.batch_no and
                                    serial_no = t.serial_no
                              order by operate_time desc)
                      where rownum <= 1)
   where exists
   (select 1
            from dm_depot v
           where t.project_no = v.project_no and
                 t.product_name = v.productname_no and t.year_no = v.year_no and
                 t.batch_no = v.batch_no and t.serial_no = v.serial_no);  commit;end;