所以，觉得有必要记录下来，这样以后再次碰到这类问题，也能从中获取解答的思路。
求一查询语句
http://bbs.csdn.net/topics/390633004
CREATE #temp (cName CHAR(1),re int)
INSERT #temp
SELECT 'A',1 UNION ALL
SELECT 'A',2 UNION ALL
SELECT 'B',3 UNION ALL
SELECT 'A',4 UNION ALL
SELECT 'A',5
如何查询得到如下的结果：
cName,re,xh
-------------------
'A',1,1
'A',2,1
'B',3,2
'A',4,3
'A',5,3
下面是我的解答：
-
select *,
-
dense_rank()
over(
order
by
case
when
exists(
select t2.re
from #temp t2
-
where t1.cname = t2.cname
-
and t1.re= t2.re +
1)
-
then (
select t2.re
from #temp t2
-
where t1.cname = t2.cname
-
and t1.re= t2.re +
1)
-
else t1.re
-
end
-
)
as xh
-
from #temp t1
-
/*
-
cName re xh
-
A 1 1
-
A 2 1
-
B 3 2
-
A 4 3
-
A 5 3
-
*/
但是这个解答是有问题的，因为当连续的记录超过3条时，就会有问题，
所以修改了一下，这个是正确的解法：
-
create
table #temp (cName
CHAR(
1),re
int)
-
-
insert
into #temp
-
SELECT
'A',
1
UNION ALL
-
SELECT
'A',
2
UNION ALL
-
SELECT
'B',
3
UNION ALL
-
SELECT
'A',
4
UNION ALL
-
SELECT
'A',
5
union all
-
SELECT
'A',
6
union all
-
SELECT
'A',
7
union all
-
SELECT
'D',
8
union all
-
SELECT
'D',
9
union all
-
SELECT
'D',
10
union all
-
select
'B',
11
union all
-
select
'A',
12
-
-
;with t
-
as
-
(
-
select *,
-
row_number()
over(
partition
by cname
order
by re)
as
rownum
-
from #temp
-
)
-
-
select cname,
-
re,
-
dense_rank()
over(
order
by
case
when
exists(
select
min(t2.re)
from t t2
-
where t1.cname = t2.cname
-
and t1.re-t1.rownum= t2.re-t2.rownum)
-
then (
select
min(t2.re)
from t t2
-
where t1.cname = t2.cname
-
and t1.re-t1.rownum= t2.re-t2.rownum)
-
else t1.re
-
end
-
)
as xh
-
from t t1
-
/*cname re xh
-
A 1 1
-
A 2 1
-
B 3 2
-
A 4 3
-
A 5 3
-
A 6 3
-
A 7 3
-
D 8 4
-
D 9 4
-
D 10 4
-
B 11 5
-
A 12 6
-
*/