在项目中，我们经常遇到或用到分页，那么在大数据量（百万级以上）下，哪种分页算法效率最优呢？我们不妨用事实说话。
测试环境
硬件：CPU 酷睿双核T5750 内存：2G
软件:Windows server 2003 + Sql server 2005
OK,我们首先创建一数据库：data_Test,并在此数据库中创建一表：tb_TestTable
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create database data_Test --创建数据库data_Test
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GO
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use data_Test
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GO
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create table tb_TestTable --创建表
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(
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id int identity(1,1) primary key,
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userName nvarchar(20) not null,
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userPWD nvarchar(20) not null,
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userEmail nvarchar(40) null
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)
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GO
然后我们在数据表中插入2000000条数据:
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--插入数据
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set identity_insert tb_TestTable on
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declare @count int
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set @count=1
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while @count<=2000000
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begin
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insert into tb_TestTable(id,userName,userPWD,userEmail) values(@count,'admin','admin888','lli0077@yahoo.com.cn')
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set @count=@count+1
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end
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set identity_insert tb_TestTable off
我首先写了五个常用存储过程：
1，利用select top 和select not in进行分页，具体代码如下：
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create procedure proc_paged_with_notin --利用select top and select not in
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(
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@pageIndex int, --页索引
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@pageSize int --每页记录数
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)
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as
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begin
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set nocount on;
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declare @timediff datetime --耗时
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declare @sql nvarchar(500)
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select @timediff=Getdate()
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set @sql='select top '+str(@pageSize)+' * from tb_TestTable where(ID not in(select top '+str(@pageSize*@pageIndex)+' id from tb_TestTable order by ID ASC)) order by ID'
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execute(@sql) --因select top后不支技直接接参数，所以写成了字符串@sql
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select datediff(ms,@timediff,GetDate()) as 耗时
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set nocount off;
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end
2,利用select top 和 select max(列键)
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create procedure proc_paged_with_selectMax --利用select top and select max(列)
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(
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@pageIndex int, --页索引
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@pageSize int --页记录数
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)
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as
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begin
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set nocount on;
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declare @timediff datetime
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declare @sql nvarchar(500)
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select @timediff=Getdate()
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set @sql='select top '+str(@pageSize)+' * From tb_TestTable where(ID>(select max(id) From (select top '+str(@pageSize*@pageIndex)+' id From tb_TestTable order by ID) as TempTable)) order by ID'
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execute(@sql)
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select datediff(ms,@timediff,GetDate()) as 耗时
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set nocount off;
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end
3,利用select top和中间变量--此方法因网上有人说效果最佳，所以贴出来一同测试
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create procedure proc_paged_with_Midvar --利用ID>最大ID值和中间变量
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(
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@pageIndex int,
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@pageSize int
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)
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as
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declare @count int
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declare @ID int
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declare @timediff datetime
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declare @sql nvarchar(500)
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begin
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set nocount on;
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select @count=0,@ID=0,@timediff=getdate()
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select @count=@count+1,@ID=case when @count<=@pageSize*@pageIndex then ID else @ID end from tb_testTable order by id
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set @sql='select top '+str(@pageSize)+' * from tb_testTable where ID>'+str(@ID)
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execute(@sql)
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select datediff(ms,@timediff,getdate()) as 耗时
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set nocount off;
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end
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4,利用Row_number() 此方法为SQL server 2005中新的方法,利用Row_number()给数据行加上索引
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create procedure proc_paged_with_Rownumber --利用SQL 2005中的Row_number()
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(
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@pageIndex int,
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@pageSize int
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)
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as
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declare @timediff datetime
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begin
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set nocount on;
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select @timediff=getdate()
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select * from (select *,Row_number() over(order by ID asc) as IDRank from tb_testTable) as IDWithRowNumber where IDRank>@pageSize*@pageIndex and IDRank<@pageSize*(@pageIndex+1)
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select datediff(ms,@timediff,getdate()) as 耗时
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set nocount off;
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end
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5，利用临时表及Row_number
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create procedure proc_CTE --利用临时表及Row_number
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(
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@pageIndex int, --页索引
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@pageSize int --页记录数
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)
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as
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set nocount on;
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declare @ctestr nvarchar(400)
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declare @strSql nvarchar(400)
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declare @datediff datetime
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begin
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select @datediff=GetDate()
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set @ctestr='with Table_CTE as
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(select ceiling((Row_number() over(order by ID ASC))/'+str(@pageSize)+') as page_num,* from tb_TestTable)';
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set @strSql=@ctestr+' select * From Table_CTE where page_num='+str(@pageIndex)
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end
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begin
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execute sp_executesql @strSql
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select datediff(ms,@datediff,GetDate())
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set nocount off;
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end
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OK,至此，存储过程创建完毕，我们分别在每页10条数据的情况下在第2页，第1000页，第10000页，第100000页，第199999页进行测试，耗时单位：ms 每页测试5次取其平均值
| 存过 | 第2页耗时 | 第1000页耗时 | 第10000页耗时 | 第100000页耗时 | 第199999页耗时 | 效率排行 |
| 1用not in | 0ms | 16ms | 47ms | 475ms | 953ms | 3 |
| 2用select max | 5ms | 16ms | 35ms | 325ms | 623ms | 1 |
| 3中间变量 | 966ms | 970ms | 960ms | 945ms | 933ms | 5 |
| 4row_number | 0ms | 0ms | 34ms | 365ms | 710ms | 2 |
| 4临时表 | 780ms | 796ms | 798ms | 780ms | 805ms | 4 |
测试结果显示：select max >row_number>not in>临时表>中间变量
于是我对效率最高的select max方法用2分法进行了扩展，代码取自互联网，我修改了ASC排序时取不到值的BUG，测试结果:
| 2分法 | 156ms | 156ms | 180ms | 470ms | 156ms | 1* |
从测试结果来看，使用2分法确实可以提高效率并使效率更为稳定，我又增加了第159999页的测试，用时仅296ms，效果相当的不错！
下面是2分法使用select max的代码，已相当完善。
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--/*-----存储过程 分页处理 孙伟 2005-03-28创建 -------*/
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--/*-----存储过程 分页处理 浪尘 2008-9-1修改----------*/
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--/*----- 对数据进行了2分处理使查询前半部分数据与查询后半部分数据性能相同 -------*/
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alter PROCEDURE proc_paged_2part_selectMax
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(
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@tblName nvarchar(200), ----要显示的表或多个表的连接
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@fldName nvarchar(500) = '*', ----要显示的字段列表
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@pageSize int = 10, ----每页显示的记录个数
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@page int = 1, ----要显示那一页的记录
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@fldSort nvarchar(200) = null, ----排序字段列表或条件
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@Sort bit = 0, ---- 排序方法，0为升序，1为降序(如果是多字段排列Sort指代最后一个排序字段的排列顺序(最后一个排序字段不加排序标记)--程序传参 如：' SortA Asc,SortB Desc,SortC ')
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@strCondition nvarchar(1000) = null, ----查询条件,不需where
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@ID nvarchar(150), ----主表的主键
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@Dist bit = 0, ----是否添加查询字段的 DISTINCT 默认0不添加/1添加
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@pageCount int = 1 output, ----查询结果分页后的总页数
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@Counts int = 1 output ----查询到的记录数
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)
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AS
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SET NOCOUNT ON
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Declare @sqlTmp nvarchar(1000) ----存放动态生成的SQL语句
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Declare @strTmp nvarchar(1000) ----存放取得查询结果总数的查询语句
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Declare @strID nvarchar(1000) ----存放取得查询开头或结尾ID的查询语句
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Declare @strSortType nvarchar(10) ----数据排序规则A
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Declare @strFSortType nvarchar(10) ----数据排序规则B
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Declare @SqlSelect nvarchar(50) ----对含有DISTINCT的查询进行SQL构造
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Declare @SqlCounts nvarchar(50) ----对含有DISTINCT的总数查询进行SQL构造
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declare @timediff datetime --耗时测试时间差
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select @timediff=getdate()
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if @Dist = 0
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begin
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set @SqlSelect = 'select '
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set @SqlCounts = 'Count(*)'
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end
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else
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begin
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set @SqlSelect = 'select distinct '
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set @SqlCounts = 'Count(DISTINCT '+@ID+')'
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end
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if @Sort=0
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begin
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set @strFSortType=' ASC '
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set @strSortType=' DESC '
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end
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else
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begin
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set @strFSortType=' DESC '
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set @strSortType=' ASC '
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end
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--------生成查询语句--------
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--此处@strTmp为取得查询结果数量的语句
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if @strCondition is null or @strCondition='' --没有设置显示条件
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begin
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set @sqlTmp = @fldName + ' From ' + @tblName
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set @strTmp = @SqlSelect+' @Counts='+@SqlCounts+' FROM '+@tblName
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set @strID = ' From ' + @tblName
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end
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else
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begin
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set @sqlTmp = + @fldName + 'From ' + @tblName + ' where (1>0) ' + @strCondition
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set @strTmp = @SqlSelect+' @Counts='+@SqlCounts+' FROM '+@tblName + ' where (1>0) ' + @strCondition
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set @strID = ' From ' + @tblName + ' where (1>0) ' + @strCondition
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end
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----取得查询结果总数量-----
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exec sp_executesql @strTmp,N'@Counts int out ',@Counts out
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declare @tmpCounts int
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if @Counts = 0
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set @tmpCounts = 1
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else
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set @tmpCounts = @Counts
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--取得分页总数
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set @pageCount=(@tmpCounts+@pageSize-1)/@pageSize
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/**//**当前页大于总页数 取最后一页**/
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if @page>@pageCount
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set @page=@pageCount
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--/*-----数据分页2分处理-------*/
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declare @pageIndex int --总数/页大小
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declare @lastcount int --总数%页大小
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set @pageIndex = @tmpCounts/@pageSize
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set @lastcount = @tmpCounts%@pageSize
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if @lastcount > 0
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set @pageIndex = @pageIndex + 1
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else
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set @lastcount = @pagesize
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--//***显示分页
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if @strCondition is null or @strCondition='' --没有设置显示条件
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begin
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if @pageIndex<2 or @page<=@pageIndex / 2 + @pageIndex % 2 --前半部分数据处理
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begin
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if @page=1
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set @strTmp=@SqlSelect+' top '+ CAST(@pageSize as VARCHAR(4))+' '+ @fldName+' from '+@tblName
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+' order by '+ @fldSort +' '+ @strFSortType
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else
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begin
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if @Sort=1
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begin
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set @strTmp=@SqlSelect+' top '+ CAST(@pageSize as VARCHAR(4))+' '+ @fldName+' from '+@tblName
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+' where '+@ID+' <(select min('+ @ID +') from ('+ @SqlSelect+' top '+ CAST(@pageSize*(@page-1) as Varchar(20)) +' '+ @ID +' from '+@tblName
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+' order by '+ @fldSort +' '+ @strFSortType+') AS TBMinID)'
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+' order by '+ @fldSort +' '+ @strFSortType
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end
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else
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begin
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set @strTmp=@SqlSelect+' top '+ CAST(@pageSize as VARCHAR(4))+' '+ @fldName+' from '+@tblName
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+' where '+@ID+' >(select max('+ @ID +') from ('+ @SqlSelect+' top '+ CAST(@pageSize*(@page-1) as Varchar(20)) +' '+ @ID +' from '+@tblName
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+' order by '+ @fldSort +' '+ @strFSortType+') AS TBMinID)'
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+' order by '+ @fldSort +' '+ @strFSortType
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end
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end
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end
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else
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begin
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set @page = @pageIndex-@page+1 --后半部分数据处理
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if @page <= 1 --最后一页数据显示
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set @strTmp=@SqlSelect+' * from ('+@SqlSelect+' top '+ CAST(@lastcount as VARCHAR(4))+' '+ @fldName+' from '+@tblName
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+' order by '+ @fldSort +' '+ @strSortType+') AS TempTB'+' order by '+ @fldSort +' '+ @strFSortType
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else
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if @Sort=1
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begin
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set @strTmp=@SqlSelect+' * from ('+@SqlSelect+' top '+ CAST(@pageSize as VARCHAR(4))+' '+ @fldName+' from '+@tblName
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+' where '+@ID+' >(select max('+ @ID +') from('+ @SqlSelect+' top '+ CAST(@pageSize*(@page-2)+@lastcount as Varchar(20)) +' '+ @ID +' from '+@tblName
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+' order by '+ @fldSort +' '+ @strSortType+') AS TBMaxID)'
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+' order by '+ @fldSort +' '+ @strSortType+') AS TempTB'+' order by '+ @fldSort +' '+ @strFSortType
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end
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else
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begin
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set @strTmp=@SqlSelect+' * from ('+@SqlSelect+' top '+ CAST(@pageSize as VARCHAR(4))+' '+ @fldName+' from '+@tblName
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+' where '+@ID+' <(select min('+ @ID +') from('+ @SqlSelect+' top '+ CAST(@pageSize*(@page-2)+@lastcount as Varchar(20)) +' '+ @ID +' from '+@tblName
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+' order by '+ @fldSort +' '+ @strSortType+') AS TBMaxID)'
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+' order by '+ @fldSort +' '+ @strSortType+') AS TempTB'+' order by '+ @fldSort +' '+ @strFSortType
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end
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end
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end
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else --有查询条件
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begin
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if @pageIndex<2 or @page<=@pageIndex / 2 + @pageIndex % 2 --前半部分数据处理
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begin
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if @page=1
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set @strTmp=@SqlSelect+' top '+ CAST(@pageSize as VARCHAR(4))+' '+ @fldName+' from '+@tblName
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+' where 1=1 ' + @strCondition + ' order by '+ @fldSort +' '+ @strFSortType
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else if(@Sort=1)
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begin
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set @strTmp=@SqlSelect+' top '+ CAST(@pageSize as VARCHAR(4))+' '+ @fldName+' from '+@tblName
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+' where '+@ID+' <(select min('+ @ID +') from ('+ @SqlSelect+' top '+ CAST(@pageSize*(@page-1) as Varchar(20)) +' '+ @ID +' from '+@tblName
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+' where (1=1) ' + @strCondition +' order by '+ @fldSort +' '+ @strFSortType+') AS TBMinID)'
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+' '+ @strCondition +' order by '+ @fldSort +' '+ @strFSortType
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end
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else
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begin
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set @strTmp=@SqlSelect+' top '+ CAST(@pageSize as VARCHAR(4))+' '+ @fldName+' from '+@tblName
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+' where '+@ID+' >(select max('+ @ID +') from ('+ @SqlSelect+' top '+ CAST(@pageSize*(@page-1) as Varchar(20)) +' '+ @ID +' from '+@tblName
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+' where (1=1) ' + @strCondition +' order by '+ @fldSort +' '+ @strFSortType+') AS TBMinID)'
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+' '+ @strCondition +' order by '+ @fldSort +' '+ @strFSortType
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end
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end
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else
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begin
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set @page = @pageIndex-@page+1 --后半部分数据处理
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if @page <= 1 --最后一页数据显示
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set @strTmp=@SqlSelect+' * from ('+@SqlSelect+' top '+ CAST(@lastcount as VARCHAR(4))+' '+ @fldName+' from '+@tblName
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+' where (1=1) '+ @strCondition +' order by '+ @fldSort +' '+ @strSortType+') AS TempTB'+' order by '+ @fldSort +' '+ @strFSortType
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else if(@Sort=1)
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set @strTmp=@SqlSelect+' * from ('+@SqlSelect+' top '+ CAST(@pageSize as VARCHAR(4))+' '+ @fldName+' from '+@tblName
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+' where '+@ID+' >(select max('+ @ID +') from('+ @SqlSelect+' top '+ CAST(@pageSize*(@page-2)+@lastcount as Varchar(20)) +' '+ @ID +' from '+@tblName
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+' where (1=1) '+ @strCondition +' order by '+ @fldSort +' '+ @strSortType+') AS TBMaxID)'
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+' '+ @strCondition+' order by '+ @fldSort +' '+ @strSortType+') AS TempTB'+' order by '+ @fldSort +' '+ @strFSortType
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else
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set @strTmp=@SqlSelect+' * from ('+@SqlSelect+' top '+ CAST(@pageSize as VARCHAR(4))+' '+ @fldName+' from '+@tblName
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+' where '+@ID+' <(select min('+ @ID +') from('+ @SqlSelect+' top '+ CAST(@pageSize*(@page-2)+@lastcount as Varchar(20)) +' '+ @ID +' from '+@tblName
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+' where (1=1) '+ @strCondition +' order by '+ @fldSort +' '+ @strSortType+') AS TBMaxID)'
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+' '+ @strCondition+' order by '+ @fldSort +' '+ @strSortType+') AS TempTB'+' order by '+ @fldSort +' '+ @strFSortType
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end
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end
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------返回查询结果-----
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exec sp_executesql @strTmp
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select datediff(ms,@timediff,getdate()) as 耗时
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--print @strTmp
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SET NOCOUNT OFF
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GO
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执行示例：exec proc_paged_2part_selectMax 'tb_testTable','ID,userName,userPWD,userEmail',10,100000,'ID',0,null,'ID',0
这种测试只在单机进行，并且没有在实际开发WEB项目中分页测试，测试项也比较单一，所以不够全面系统，但从其效率相比上，我们可以在数据库分页算法上进行有效的控制。
