Question

分组在from和toloc完成，一组由usrid

表示

Table :

from   toloc  usrid
a        b      1
c        d      1       --- group 1
e        f      1
-------------------
a        b      2
c        d      2       --- group 2  
e        f      2
----------------------
a        b      3
c        d      3       --- group 3
h        k      3

在组设置查询后需要结果???

from   toloc  usrid
a        b      1
c        d      1       --- group 1 & 3 combined to form 1 group
e        f      1
-------------------
a        b      2![alt text][1]
c        d      2       --- group 2  
h        k      2

如何实现结果集。我必须在sql中对类似的记录集进行分组。是否可以使用汇总或新的分组集。我无法理解它。

Answer 1

我挖出了这个老问题。假设没有重复的行，它应该工作。

我首先解决了你所链接的那个，然后重新编写它以匹配这个，所以字段的名称与你的例子相比会有所不同。

DECLARE @t TABLE (fromloc VARCHAR(30), toloc VARCHAR(30), usr_history INT)

INSERT @t VALUES ('a', 'b', 1)
INSERT @t VALUES ('c', 'b', 1)
INSERT @t VALUES ('e', 'f', 1)
INSERT @t VALUES ('a', 'b', 2)
INSERT @t VALUES ('c', 'b', 2)
INSERT @t VALUES ('e', 'f', 2)
INSERT @t VALUES ('a', 'b', 3)
INSERT @t VALUES ('c', 'd', 3)
INSERT @t VALUES ('h', 'k', 3)

;WITH c as
(
SELECT t1.usr_history h1, t2.usr_history h2, COUNT(*) COUNT 
FROM @t t1
JOIN @t t2 ON t1.fromloc = t2.fromloc and t1.toloc = t2.toloc and t1.usr_history < t2.usr_history 
GROUP BY t1.usr_history, t2.usr_history
), 
d as (
SELECT usr_history h, COUNT(*) COUNT FROM @t GROUP BY usr_history
), 
e as (
SELECT d.h FROM d JOIN c ON c.COUNT = d.COUNT and c.h2 = d.h
JOIN d d2 ON d2.COUNT=c.COUNT and d2.h= c.h1
)
SELECT fromloc, toloc, DENSE_RANK() OVER (ORDER BY usr_history) AS 'usrid' 
FROM @t t 
WHERE NOT EXISTS (SELECT 1 FROM e WHERE e.h = t.usr_history)

Answer 2

这个问题的答案在这里：https://stackoverflow.com/a/6727662/195446

另一种方法是使用FOR XML PATH作为记录集的签名。

在sql中分组记录集

2 个答案: