sql - INNER JOIN 实现最大值(value)

Question

我想知道是否有可能内在加入最大的值(value)。

举个例子

SELECT *
FROM Vehicle v
INNER JOIN VehicleCost vc ON v.VehicleWeight > vc.WeightFrom AND c.VehicleWeight < vc.WeightTo

但是如果 v.VehicleWeightTotal > v.VehicleWeight 我希望用它来替换内部连接上的 v.VehicleWeight。因此，每辆车可能会有不同的连接。

我将如何在联接中进行该检查？

示例:

tblVehicle
VehicleId  VehicleWeight VehicleWeightTotal 
1               12              15
2               1               8
3               16              20

tblVehicleCost
WeightFrom    WeightTo  Dollars
0               5         1
6               11        8
12              16        9 
17              20       15

所以:

Vehicle 1 = 9
Vehicle 2 = 8
Vehicle 3 = 15

Answer 1

您的要求可以更简单地表达为:

use the greater of VehicleWeight and VehicleWeightTotal when joining

这是在 SQL 中表达的方式:

SELECT *
FROM Vehicle v
INNER JOIN VehicleCost vc 
   ON (case
         when VehicleWeightTotal > VehicleWeight then VehicleWeightTotal
         else VehicleWeight
       end) between vc.WeightFrom AND vc.WeightTo;

我冒昧地将您的范围检查更改为使用 between ，但如果不能匹配等于范围限制的值 - 即使用 >=和<=在您的查询中 - 然后只需重复 case范围每一边的声明。