SQL server 2005新增的几个函数,分别是row_number( )、rank( )、,DENSE_RANK( )、ntile( )下面以实例分别简单讲解。
1.row_number( )
先来点数据,先建个表
SET NOCOUNT ON
CREATE TABLE Person(
FirstName VARCHAR(10),
Age INT,
Gender CHAR(1))
INSERT INTO Person VALUES ('Ted',23,'M')
INSERT INTO Person VALUES ('John',40,'M')
INSERT INTO Person VALUES ('George',6,'M')
INSERT INTO Person VALUES ('Mary',11,'F')
INSERT INTO Person VALUES ('Sam',17,'M')
INSERT INTO Person VALUES ('Doris',6,'F')
INSERT INTO Person VALUES ('Frank',38,'M')
INSERT INTO Person VALUES ('Larry',5,'M')
INSERT INTO Person VALUES ('Sue',29,'F')
INSERT INTO Person VALUES ('Sherry',11,'F')
INSERT INTO Person VALUES ('Marty',23,'F')
直接用例子说明问题:
SELECT ROW_NUMBER() OVER (ORDER BY Age) AS [Row Number by Age],
FirstName,
Age
FROM Person
出现的数据如下
Row Number by Age FirstName Age
-------------------------- ---------- --------
1 Larry 5
2 Doris 6
3 George 6
4 Mary 11
5 Sherry 11
6 Sam 17
7 Ted 23
8 Marty 23
9 Sue 29
10 Frank 38
11 John 40
可以观察到,是根据年龄升序排列了，并且row_number()是给出了序列号了,这个序列号被重命名为Row Number by Age,与sql server2000对比:如果在sql server2000中实现相对麻烦一些，我们可以利用IDENTITY()函数实现，但IDENTITY()函数只能用在sql server2000临时表中，因此需要将数据检索到临时表里。select identity(int,1,1) as [Row Number by Age],FirstName,Age into #A from Person order by Ageselect * from #Adrop table #a如果不想按年龄排序,可以这样写SELECT ROW_NUMBER() OVER (ORDER BY (SELECT 1)) AS [Row Number by Record Set],
FirstName,
Age
FROM Person另外一个例子SELECT ROW_NUMBER() OVER (PARTITION BY Gender ORDER BY Age) AS [Partition by Gender],
FirstName,
Age,
Gender
FROM Person这里是按性别划分区间了，同一性别再按年龄来排序,输出结果如下
Partition by Gender FirstName Age Gender
-------------------- ---------- ----------- ------
1 Doris 6 F
2 Mary 11 F
3 Sherry 11 F
4 Sue 29 F
1 Larry 5 M
2 George 6 M
3 Sam 17 M
4 Ted 23 M
5 Marty 23 M
6 Frank 38 M
7 John 40 M注意,姓名M开始,序号又从1,2,3开始了
2.RANK( )函数 先看例子SELECT RANK() OVER (ORDER BY Age) AS [Rank by Age],
FirstName,
Age
FROM Person输出如下:Rank by Age FirstName Age
-------------------- ---------- -----------
1 Larry 5
2 Doris 6
2 George 6
4 Mary 11
4 Sherry 11
6 Sam 17
7 Ted 23
7 Marty 23
9 Sue 29
10 Frank 38
11 John 40看到了么,同年岭的话,将有相同的顺序,顺序成1,2,2,4了。与sql server2000对比:出现了RANK()函数实在是方便,在sql server2000里实现排序并列的问题麻烦很多。select [Rank by Age]=isnull((select count(*) from person where Age>A.Age),0)+1,FirstName,Age from Person A order by [Rank by Age] SELECT RANK() OVER(PARTITION BY Gender ORDER BY Age) AS [Partition by Gender],FirstName, Age, Gender FROM Person输出为Partition by Gender FirstName Age Gender
-------------------- ---------- ----------- ------
1 Doris 6 F
2 Mary 11 F
2 Sherry 11 F
4 Sue 29 F
1 Larry 5 M
2 George 6 M
3 Sam 17 M
4 Ted 23 M
4 Marty 23 M
6 Frank 38 M
7 John 40 M可以看到,按性别分组了,每个性别分组里,继续是用了rank( )函数
3.DENSE_RANK( )函数
SELECT DENSE_RANK() OVER (ORDER BY Age) AS [Dense Rank by Age],
FirstName,
Age
FROM Person
输出结果为:
Dense Rank by Age FirstName Age
-------------------- ---------- -----------
1 Larry 5
2 Doris 6
2 George 6
3 Mary 11
3 Sherry 11
4 Sam 17
5 Ted 23
5 Marty 23
6 Sue 29
7 Frank 38
8 John 40
看到了么,和rank函数区别是,顺序始终是连续的,Doris 和George同年,都是排第2位,但之后的mary不象rank函数那样排第4,而是排第3位了
4.ntile( )函数
SELECT FirstName,
Age,
NTILE(3) OVER (ORDER BY Age) AS [Age Groups]
FROM Person
输出结果：
FirstName Age Age Groups
---------- ----------- --------------------
Larry 5 1
Doris 6 1
George 6 1
Mary 11 1
Sherry 11 2
Sam 17 2
Ted 23 2
Marty 23 2
Sue 29 3
Frank 38 3
John 40 3
这个函数按照ntile(n)中的N,把记录强制分成多少段,11条记录现在分成3段了,lary到mary是第1段,sherry到maty是第2段,sue到john是第3段了。
最近给客户做了个查看通话记录的小功能，不论是查询还是显示都很快的完成了。唯一的问题就是因为数据记录太多[上万条，且每天都已几十近百条的速度增长]，显示速度太慢。我用的是VS2005 GridView自带的分页功能，显然数据太多GridView自身的分页功能已经不在适用。本来想用存储过程，但感觉太麻烦。在网上淘了半天，终于淘了个非常好的利用SQLServer2005自带的Row_Number()函数做的SQL语句分页的方法。闲话少说，看代码：
declare @pageIndex int2
declare @pageSize int3
set @pageIndex=14
set @pageSize=265
6
SELECT * FROM (SELECT ROW_NUMBER() OVER(ORDER BY id DESC) AS rownum,7
id, callerno, calleeno, uid, callbegin,callend,bs8
FROM [222.43.48.95].lyzj.dbo.billlog where uid='007') AS D9
WHERE rownum BETWEEN (@pageIndex-1)*@pageSize+1 AND @pageIndex*@pageSize10
ORDER BY id DESC 上面就是分页的SQL语句，但是实际使用的时候，问题又出现了。我用的是ASPNETPager分页控件，查看的时候，第一页的数据总是无法显示；调试了半天才找出原因。原来是早先用GridView自身的分页时，分页的索引是从0开始的，而现在的分页却是从1 开始。两者搅在一起，不出问题都怪了，呵呵，搞定！
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