Question

我有一些项目，里面有设计。因此，一个项目可以有多个设计。

项目表：

+------------+------+
| ProjectKey | Name |
+------------+------+

ProjectDesignTable：

+------------+-----------+
| ProjectKey | DesignKey |
+------------+-----------+

设计表：

+-----------+------+--------------+----------------+-----------------+
| DesignKey | Name | DesignNumber | DesignTypeGuid | ParentDesignKey |
+-----------+------+--------------+----------------+-----------------+

所以我有一个这样的选择查询：

SELECT
      *
      FROM [project] AS [p]
          INNER JOIN [ProjectDesign] AS [pd] ON [p].[ProjectKey] = [pd].[ProjectKey]
          INNER JOIN [Design] AS [d] ON [d].[DesignKey] = [pd].[DesignKey]
      WHERE [d].[DesignTypeGuid] = '54FBBC23-CB9A-4311-9D7F-0DD7A774F33D'

我在每个项目中得到的所有设计都有DesignTypeGuid: '54FBBC23-CB9A-4311-9D7F-0DD7A774F33D'

我想要实现的是在每个项目的第一个设计键之后获取行，例如，如果我有此行：

    +------------+--------------+-----------+----------------------------------------+-----------------+
| ProjectKey | DesignNumber | DesignKey |               DesignType               | ParentDesignKey |
+------------+--------------+-----------+----------------------------------------+-----------------+
|        152 |            1 |       187 | '54FBBC23-CB9A-4311-9D7F-0DD7A774F33D' | NULL            |
|        152 |            2 |      1316 | '54FBBC23-CB9A-4311-9D7F-0DD7A774F33D' | NULL            |
|       1171 |            1 |      1206 | '54FBBC23-CB9A-4311-9D7F-0DD7A774F33D' | NULL            |
|       1171 |            2 |      1317 | '54FBBC23-CB9A-4311-9D7F-0DD7A774F33D' | NULL            |
|       1171 |            3 |      1401 | '54FBBC23-CB9A-4311-9D7F-0DD7A774F33D' | NULL            |
+------------+--------------+-----------+----------------------------------------+-----------------+

我渴望得到的结果是：

 152 |            2 |      1316 | '54FBBC23-CB9A-4311-9D7F-0DD7A774F33D'
1171 |            2 |      1317 | '54FBBC23-CB9A-4311-9D7F-0DD7A774F33D' 
1171 |            3 |      1401 | '54FBBC23-CB9A-4311-9D7F-0DD7A774F33D'

一旦得到这个信息，我想用每个项目I.E的第一个designKey更新该行的ParentDesignKey列：

152 |            2 |      1316 | '54FBBC23-CB9A-4311-9D7F-0DD7A774F33D'

应该为第一个设计的"187"（DesignKey）更新ParentKey

我该如何实现？问候

Answer 1

这是一个交叉应用解决方案：

update d set ParentDesignKey=firstDesignKey
from Design d
cross apply
(
    select top 1 Designkey as firstDesignKey
    from Design dfirst
    inner join ProjectDesign AS pd ON dfirst.DesignKey = [pd].[DesignKey]
    where d.DesignKey = [pd].[DesignKey]
    order by dfirst.DesignNumber asc
)q

Answer 2

假设我理解了这个问题，则可以使用 ~~lag~~ first_value来获取{{1} }与当前行相同，但DesignKey较低：

ProjectKey

对于您发布的样本数据，此查询应为您提供以下结果集：

DesignNumber

另外，请注意，由于您在任何地方都不使用其中的任何列，因此实际上不需要加入SELECT ProjectKey, DesignNumber, DesignKey, DesignType, FIRST_VALUE(DesignKey) OVER(PARTITION BY ProjectKey ORDER BY DesignNumber) AS ParentDesignKey FROM [ProjectDesign] AS [pd] INNER JOIN [Design] AS [d] ON [d].[DesignKey] = [pd].[DesignKey] WHERE [d].[DesignTypeGuid] = '54FBBC23-CB9A-4311-9D7F-0DD7A774F33D'表。

Answer 3

SELECT p.ProjectKey, max(DesignNumber), d.DesignKey, DesignType 
FROM [project] AS [p]
      INNER JOIN [ProjectDesign] AS [pd] ON [p].[ProjectKey] = [pd].[ProjectKey]
      INNER JOIN [Design] AS [d] ON [d].[DesignKey] = [pd].[DesignKey]
WHERE [d].[DesignTypeGuid] = '54FBBC23-CB9A-4311-9D7F-0DD7A774F33D'
GROUP BY p.ProjectKey, d.DesignKey, DesignType

获取父表的最后一行

3 个答案: