查找不同表中不存在的对

Question

我有一个表(订单)与订单ID,位置1,位置2和另一个表(里程),位置1和位置2.

我正在使用Except操作以不在里程中的订单返回这些位置对.但我不知道如何还能返回属于这些对的相应order_id(里程表中不存在order_id).我唯一能想到的是使用外部select语句来搜索那些位置对的订单.我没试过,但我正在寻找其他选择.

我有类似的东西.

SELECT location_id1, location_id2  
FROM orders 
except
SELECT lm.origin_id, lm.dest_id
from mileage

我怎样才能检索这些对的订单ID？

Answer 1

您可以尝试使用Not Exists语句:

Select O.order_id, O.location_id1, O.location_id2
From orders As O
Where Not Exists    (
                    Select 1
                    From mileage As M1
                    Where M1.origin_id = O.location_id1
                        And M1.dest_id = O.location_id2
                    )

另一种解决方案,如果你真的想使用Except

Select O.order_id, O.location_id1, O.location_id2
From Orders As O
Except
Select O.order_id, O.location_id1, O.location_id2
From Orders As O
    Join Mileage As M
        On M.origin_id = O.location_id1
            And M.dest_id = O.location_id2