oracle中如何选择两个max函数

Question

我需要从这里的两个表中选择最大值。我怎样才能做到这一点？这是我的预言机代码：

select t_order_demand.customer_name,
max(t_order_log.seq) as "seq",
max(t_order_log.extern_order_status) as "extern"
from t_order_demand,t_order_log
where t_order_demand.order_id=t_order_log.order_id
and t_order_demand.order_id like '%88%'
group by t_order_log.seq,t_order_log.extern_order_status,t_order_demand.customer_name;

结果是有两个客户名称，seq 列是 1，并且有两个 extern 0 和 2。我只希望他们显示 1 个客户名称、1 个最大 seq 和 1 个最大 extern。但是怎么做？请帮帮我。

Answer 1

您需要从GROUP BY 中删除 seq, extern_order 也将其更改为使用显式连接

    select t_order_demand.customer_name,
    max(t_order_log.seq) as "seq",
    max(t_order_log.extern_order_status) as "extern"
    from t_order_demand
    JOIN t_order_log
    ON t_order_demand.order_id=t_order_log.order_id
    and t_order_demand.order_id like '%88%'
    group by t_order_demand.customer_name

如果您只希望这组客户中有一个客户

SELECT * FROM  (
  select t_order_demand.customer_name,
  max(t_order_log.seq) as "seq",
  max(t_order_log.extern_order_status) as "extern"
  from t_order_demand
  JOIN t_order_log
  ON t_order_demand.order_id=t_order_log.order_id
  and t_order_demand.order_id like '%88%'
  group by t_order_demand.customer_name 
) WHERE ROW_NUM =1