Question

我正在尝试在分层数据集上编写复杂的CASE语句。

这是包含样本数据的表格：

Level  Parent     Child       IsDirector
----------------------------------------
0      NULL       SteveJobs     NO
1      SteveJobs  TimCook       YES
2      TimCook    Greg          NO
3      Greg       Mark          NO
4      Mark       Jack          NO
4      Mark       Kim           NO
4      Mark       Tyler         NO
4      Mark       Emma          NO

我正在尝试编写SQL查询来查找某个人的导演。如果我查询Kim，结果应该是这样的。

Parent  Child   Director    
-------------------------
Mark    Kim     TimCook

这是我写的查询。

SELECT 
    A.Parent, A.Child,
    CASE A.IsDirector 
        WHEN 'YES' 
           THEN A.Child
        WHEN 'NO' 
           THEN CASE 
                   WHEN (A.IsDirector = 'NO' AND A.Parent IS NOT NULL) 
                      THEN A.Parent
                      ELSE (SELECT  
                                CASE WHEN B.IsDirector = 'YES' 
                                        THEN B.Parent
                                END AS Director
                            FROM @Org B 
                            WHERE B.Child = A.Parent) 
                END 
    END AS Director,
    A.IsDirector
FROM
    @Org A
WHERE 
    Child = 'Kim'

结果是

Parent  Child   Director  IsDirector
------------------------------------
Mark    Kim     Mark      NO

下面是SQL小提琴。抱歉，我不知道如何格式化上述代码。

http://sqlfiddle.com/#!6/b5830

Answer 1

也许有一个递归的cte

Declare @YourTable table (Level int,Parent varchar(50),Child varchar(50),IsDirector varchar(50))
Insert into @YourTable values
(0,NULL,'SteveJobs','NO'),
(1,'SteveJobs','TimCook','YES'),
(2,'TimCook','Greg','NO'),
(3,'Greg','Mark','NO'),
(4,'Mark','Jack','NO'),
(4,'Mark','Kim','NO'),
(4,'Mark','Tyler','NO'),
(4,'Mark','Emma','NO')

Declare @Fetch varchar(50)='Kim'

;with cteHB as (
      Select Child
            ,Parent
            ,Lvl=1
            ,Director=case when IsDirector='Yes' then Child else '' end
      From   @YourTable 
      Where  Child=@Fetch
      Union  All
      Select R.Child
            ,R.Parent
            ,P.Lvl+1
            ,Director=case when IsDirector='Yes' then R.Child else '' end
      From   @YourTable R
      Join   cteHB P on P.Parent = R.Child)
Select A.*
      ,B.Director
 From  @YourTable A
 Join  cteHB B on (A.Child=@Fetch and Director<>'')

返回

Level   Parent  Child   IsDirector  Director
4       Mark    Kim     NO          TimCook

只是为了好玩，要查看路径，您可以用

替换文件SELECT

Select Lvl = Row_Number() over (Order By Lvl Desc)
      ,Child
      ,Parent
      ,Director
From cteHB
Order By 1

复杂的Hieraechical遍历Case语句T-SQL

1 个答案: