SQL Server 2008 R2：递归查询

debugcn 发表于 Dev

麦

我的表具有两列，即可乐和colb，如下所示：

表：测试

create table Test
(
 cola int,
 colb int
);

我输入的记录是：

Cola   Colb
------------
1      2
1      3
1      4
2      5
2      6
2      3
3      2
3      4
3      7
3      10
10     11
11      12
11     13
11     14
12     15
13     16 
14     99
15     88
16     77

注意：现在，我只想显示与我通过的值相关的记录。例如，如果我将值传递为1，则它应该向我显示连接的数字，并像树一样形成连接。

对于上述要求，我从黑暗骑士那里获得了脚本，如下所示，效果很好。

;WITH CTE AS
(
   SELECT COLA,COLB,','+CAST(COLA AS VARCHAR(MAX))+',' AS CHCK FROM test WHERE COLA=1
   UNION ALL
   SELECT C1.COLA,C1.COLB,C.CHCK+CAST(C1.cola AS VARCHAR(MAX))+','
   FROM CTE C INNER JOIN test C1 ON  C.colb = C1.cola
   WHERE CHARINDEX(','+CAST(C.colb AS VARCHAR(MAX))+',',C.CHCK)=0
),
OUTERCTE AS
(   
    SELECT DISTINCT COLA,COLB,ROW_NUMBER() OVER(PARTITION BY Colb ORDER BY Cola) rn FROM CTE --ORDER BY COLA
)
SELECT Cola,Colb FROM OUTERCTE
WHERE rn<=1
ORDER BY CASE WHEN Cola = 1 THEN 1 ELSE 2 END;

这给了我这个：

----------------
Cola        Colb
----------------
1           2   
1           3   
1           4   
2           5   
2           6   
3           7   
3           10  
10          11  
11          12  
11          13  
11          14  
12          15  
13          16  
16          77  
15          88  
14          99

要求：现在我想显示记录级别。

预期结果：

    ------------------------------
    Cola        Colb        Level
    ------------------------------
    1           2           1
    1           3           1
    1           4           1
    2           5           2
    2           6           2
    3           7           2
    3           10          2
    10          11          3
    11          12          4
    11          13          4
    11          14          4
    12          15          5   
    13          16          5
    16          77          6
    15          88          6
    14          99          5

奥萨马·奥拉比

;WITH CTE AS
(
   SELECT COLA,COLB
                 ,','+CAST(COLA AS VARCHAR(MAX))+',' AS CHCK 
                , 1 as lvl FROM #Test WHERE COLA=1
   UNION ALL
   SELECT C1.COLA,C1.COLB  ,C.CHCK+CAST(C1.cola AS VARCHAR(MAX))+',' 
                            , c.lvl+1 
   FROM CTE C INNER JOIN #Test C1 ON  C.colb = C1.cola
    WHERE CHARINDEX(','+CAST(C.colb AS VARCHAR(MAX))+',',C.CHCK)=0 

),
cte2 as (
select * , ROW_NUMBER() over (partition by colb order by lvl)as rn From CTE
)
select cola,colb,lvl from cte2 where rn = 1

本文收集自互联网，转载请注明来源。

如有侵权，请联系[email protected] 删除。