过滤 SQL 查询返回的结果

Question

我整个下午都在努力解决这个问题 - 看起来很简单，但我一定错过了什么！

我有一个返回一些数据的查询，它返回的两列是“PackageWeight”和“PackageGroup”。本质上，我想过滤这些数据，只为每个“PackageGroup”显示一行 - 这应该是“PackageWeight”列中值最高的行。

这看起来很简单，但我无法使用 TOP 1 和 GROUP BY 的组合在 SQL Server 中工作。我一定是错过了什么！

    SELECT VendorID, PackageID, PackageWeight, PackageGroup
  FROM (SELECT VendorID, COUNT(*) AS qty
          FROM VendorServices
         GROUP BY VendorID
       ) cs
  JOIN (SELECT PackageServices.PackageID, lookupPackages.PackageWeight, lookupPackages.PackageGroup, COUNT(*) AS qty
          FROM PackageServices
          JOIN lookupPackages ON PackageServices.PackageID = lookupPackages.PackageID
          GROUP BY PackageServices.PackageID, lookupPackages.PackageWeight, lookupPackages.PackageGroup
       ) ps ON cs.qty >= ps.qty
  WHERE (SELECT COUNT(*)
          FROM VendorServices cs2
          JOIN PackageServices ps2 ON cs2.ServiceTypeID = ps2.ServiceID
         WHERE cs2.VendorID = cs.VendorID
           AND ps2.PackageID = ps.PackageID
       ) = ps.qty

此查询返回我需要过滤的完整数据集。但是到目前为止我的尝试都失败了:(

非常感谢任何帮助！

编辑 - 感谢下面的贡献者，到目前为止我有以下查询：

with result_cte as
(
SELECT VendorID, PackageID, PackageWeight, PackageGroup,
    RANK() over (partition by PackageGroup order by PackageWeight desc) as [rank]
FROM (SELECT VendorID, COUNT(*) AS qty
    FROM VendorServices
    GROUP BY VendorID
    ) cs
JOIN (SELECT PackageServices.PackageID, lookupPackages.PackageWeight, lookupPackages.PackageGroup, COUNT(*) AS qty
    FROM PackageServices
    JOIN lookupPackages ON PackageServices.PackageID = lookupPackages.PackageID
    GROUP BY PackageServices.PackageID, lookupPackages.PackageWeight, lookupPackages.PackageGroup
    ) ps ON cs.qty >= ps.qty
WHERE (SELECT COUNT(*)
    FROM VendorServices cs2
    JOIN PackageServices ps2 ON cs2.ServiceTypeID = ps2.ServiceID
    WHERE cs2.VendorID = cs.VendorID
    AND ps2.PackageID = ps.PackageID
    ) = ps.qty
)

select *
from result_cte
WHERE [rank] = 1
ORDER BY VendorID

到目前为止，一切都很好。我仍然会看一下@gbn 建议的 APPLY 运算符，因为这对我来说是新的 - 我仍然需要做一些测试以确保这个查询在 100% 的时间内工作。不过初步迹象很好！

感谢迄今为止做出贡献的所有人。

编辑 2 - 遗憾的是，在使用更多示例数据填充数据库后，此查询无法正常工作。好像漏掉了一些条目。

也许我需要多解释一下这里发生了什么。我的原始查询返回的数据列出了系统中的每个客户，以及派生的 PackageID（由该查询计算）以及在查找表中分配给该包裹的权重和组。

我需要过滤原始结果表，以便我从每个组中为每个客户获得不超过一个包（每个客户可能从一个或多个组中获得一个包，但可能不会从每个组中获得一个包）

明天我会重新审视这个问题，因为我想我可能会处于“只见树木不见森林”的境地！

谢谢大家。

Answer 1

你可以试试这个吗？如果您在同一组中有多个具有相同权重的记录，则它不是防弹的。还有其他处理方法。

with result_cte as
(
SELECT VendorID, PackageID, PackageWeight, PackageGroup
FROM (SELECT VendorID, COUNT(*) AS qty
    FROM VendorServices
    GROUP BY VendorID
    ) cs
JOIN (SELECT PackageServices.PackageID, lookupPackages.PackageWeight, lookupPackages.PackageGroup, COUNT(*) AS qty
    FROM PackageServices
    JOIN lookupPackages ON PackageServices.PackageID = lookupPackages.PackageID
    GROUP BY PackageServices.PackageID, lookupPackages.PackageWeight, lookupPackages.PackageGroup
    ) ps ON cs.qty >= ps.qty
WHERE (SELECT COUNT(*)
    FROM VendorServices cs2
    JOIN PackageServices ps2 ON cs2.ServiceTypeID = ps2.ServiceID
    WHERE cs2.VendorID = cs.VendorID
    AND ps2.PackageID = ps.PackageID
    ) = ps.qty
)

select *
from result_cte
where result_cte.PackageWeight = (select top 1 highestweight.PackageWeight from result_cte highestweight
                                where highestweight.PackageGroup = result_cte.PackageGroup
                                order by highestweight.PackageWeight desc)

或者你可以这样做：

with result_cte as
(
SELECT VendorID, PackageID, PackageWeight, PackageGroup,
    ROW_NUMBER() over (partition by PackageGroup order by PackageWeight desc) as [row]
FROM (SELECT VendorID, COUNT(*) AS qty
    FROM VendorServices
    GROUP BY VendorID
    ) cs
JOIN (SELECT PackageServices.PackageID, lookupPackages.PackageWeight, lookupPackages.PackageGroup, COUNT(*) AS qty
    FROM PackageServices
    JOIN lookupPackages ON PackageServices.PackageID = lookupPackages.PackageID
    GROUP BY PackageServices.PackageID, lookupPackages.PackageWeight, lookupPackages.PackageGroup
    ) ps ON cs.qty >= ps.qty
WHERE (SELECT COUNT(*)
    FROM VendorServices cs2
    JOIN PackageServices ps2 ON cs2.ServiceTypeID = ps2.ServiceID
    WHERE cs2.VendorID = cs.VendorID
    AND ps2.PackageID = ps.PackageID
    ) = ps.qty
)

select *
from result_cte
where [row] = 1

Answer 2

你可以使用 MAX 函数：

SELECT * FROM #one
lbs groups
5   0
4   0
1   0
9   1
2   1     

SELECT groups,MAX(lbs)
FROM #one
GROUP BY groups

groups  (No column name)
0   5
1   9

Answer 3

如果多个包裹在一组中具有相同的最大重量，您是否愿意接受单个任意供应商和PackageID？如果可以，只需在它们上加上PackageWeight：

SELECT max(VendorID), max(PackageID), max(PackageWeight), PackageGroup
...
GROUP BY PackageGroup

否则，您将需要像 E.Y.建议并执行嵌套查询，首先找到每个组的最大权重，然后自己处理重复项（如果有）。

Answer 4

感谢 Eric.K.Yung 的帖子 - 我终于使用他的查询解决了这个问题，但将 VendorID（实际上是 CustomerID）添加到查询的“分区依据”部分。这样可以确保为所有客户退回包裹。

感谢所有做出贡献的人。最后的查询是：

with result_cte as
(
SELECT VendorID, PackageID, PackageWeight, PackageGroup,
    ROW_NUMBER() over (partition by PackageGroup, VendorID order by PackageWeight desc) as [row]
FROM (SELECT VendorID, COUNT(*) AS qty
    FROM VendorServices
    GROUP BY VendorID
    ) cs
JOIN (SELECT PackageServices.PackageID, lookupPackages.PackageWeight, lookupPackages.PackageGroup, COUNT(*) AS qty
    FROM PackageServices
    JOIN lookupPackages ON PackageServices.PackageID = lookupPackages.PackageID
    GROUP BY PackageServices.PackageID, lookupPackages.PackageWeight, lookupPackages.PackageGroup
    ) ps ON cs.qty >= ps.qty
WHERE (SELECT COUNT(*)
    FROM VendorServices cs2
    JOIN PackageServices ps2 ON cs2.ServiceTypeID = ps2.ServiceID
    WHERE cs2.VendorID = cs.VendorID
    AND ps2.PackageID = ps.PackageID
    ) = ps.qty
)

select *
from result_cte
where [row] = 1