Question

我有t_cust表，我想显示客户的最新账单月和账单金额。我写了查询，但对于大数据，它将花费很多时间。有任何简单的寻找最新法案月的逻辑？

create table t_cust
(
cust_id     varchar2(3),
b_year      varchar2(4),
b_month     varchar2(2),
b_amount    number
);

insert into t_cust values('ABC','2015','11',100);
insert into t_cust values('ABC','2015','12',200);
insert into t_cust values('ABC','2016','01',300);
insert into t_cust values('XYZ','2016','01',1000);
insert into t_cust values('XYZ','2016','02',2000);
insert into t_cust values('XYZ','2016','03',3000);

commit;

    select cust_id,substr(to_date(b_year*100+b_month,'YYYYMM'),4)latest_bill_mth,b_amount bill_amount
    from   t_cust
    where  (cust_id,b_year*100+b_month) in (
                                            select cust_id,max(b_year*100+b_month)
                        from   t_cust
                        group by cust_id
                        );

Answer 1

看起来像Oracle，所以只需使用ROW_NUMBER / RANK：

select ...
from
 (
   select ...
      ,row_number() 
       over (partition by t_cust
             order by year desc, month desc) as rn
 ) dt
where rn = 1

显示最新的账单月

1 个答案: