Question

我有一些看起来像这样的模型：父母与Child有1-2-M的关系，而Child与Sub-Child有1-2-M的关系。

Parent
------
Parent_ID


Child
-----
Child_ID,
Parent_ID


Sub-Child
---------
Child_ID,
Version_Number (numeric),
Sent (date),
Void (date)

我想要一个查询，它返回一个唯一的parent_id列表，其中相关子子的最新版本（由version_number判断）为'sent' == null，但是'void' != null。

我一直在脑子里咀嚼这个，无法解决问题。

非常感谢任何建议。

谢谢，

罗伯特

Answer 1

这将是：

;WITH CTE_LatestSubChildren AS
(
    SELECT Parent_ID, Latest_Version_Number = max(sc.Version_Number)
    FROM
       Child c
       JOIN [Sub-Child] sc on c.Child_ID = sc.Child_ID
    GROUP BY c.Parent_ID

)
SELECT
    ParentID
FROM
    CTE_LatestSubChildren lsc
    JOIN Child c 
        on lsc.Parent_ID = c.Parent_ID
    JOIN [Sub-Child] sc 
        ON sc.Child_ID = c.Child_ID    
        AND sc.version_number = lsc.Latest_Version_Number   
        AND sc.Sent IS NULL    
        AND sc.Void IS NOT NULL

请注意，这可能需要修改，因为它未经过测试，并且不完全清楚最新版本相同的多个子记录会发生什么。

Answer 2

我不是我可以测试它的地方，但听起来你需要一个子查询来提取每个孩子的最大版本号，然后自我加入以获得其余的子子信息。这样的事情就是我的想法：

SELECT DISTINCT
  Parent_ID
FROM
  Parent JOIN Child
    ON Parent.Parent_ID = Child.Parent_ID
  JOIN (
    SELECT Child_ID, MAX(Version_Number)
    FROM Sub-Child
    GROUP BY Child_ID ) AS MaxSubchild
  JOIN Sub-Child
    ON Sub-Child.Child_ID = MaxSubchild.Child_ID AND
      Sub-Child.Version_Number = MaxSubchild.Version_Number
WHERE
  SUb-Child.Sent IS NULL AND
  Sub-Child.Void IS NOT NULL;

Answer 3

首先通过child_id获取最高版本：

select child_id, max(version_number) as version_number
from subchild
group by child_id

然后将其作为子查询加入子子项和子项，并应用where where条件。

Answer 4

或者，如果没有子查询，请尝试

SELECT DISTINCT p.parent_id
FROM sub_children sc
  LEFT JOIN children c ON sc.parent_id = c.child_id
  LEFT JOIN parents p ON c.parent_id = p.parent_id
WHERE sc.sent == null, but sc.void != null

Answer 5

您也可以使用Rank（）：

SELECT DISTINCT TOP 100 PERCENT ST.Parent_ID
FROM
(
    SELECT RANK() OVER (PARTITION BY C.Parent_ID ORDER BY SC.Version_Number DESC) AS [RANK], 
    C.Parent_ID, SC.Sent, SC.Void
    FROM Child C 
    INNER JOIN Sub_Child SC ON C.Child_ID = SC.Child_ID
) ST
WHERE [RANK] = 1
AND [Sent] IS NULL AND [Void] IS NOT NULL

SQL：选择最新子子位置

5 个答案: