（3.15）常用知识-sql server分页

推荐使用row_number over()方法，或2012以上使用offset

PageSize =

PageNumber =

方法一：(最常用的分页代码， top / not in)

　　select top  UserId from UserInfo where UserId not in (select top  UserId from UserInfo order by UserId) order by UserId

备注： 注意前后的order by 一致

方法二：(not exists， not in 的另一种写法而已)

　　select top  * from UserLog where not exists (select  from (select top  LogId from UserLog order by LogId) a where a.LogId = UserLog.LogId) order by LogId

备注：EXISTS用于检查子查询是否至少会返回一行数据，该子查询实际上并不返回任何数据，而是返回值True或False。此处的 select  from 也可以是select  from，select LogId from, select * from 等等，不影响查询。而且select  效率最高，不用查字典表。效率值比较： > anycol > *

方法三：(top / max， 局限于使用可比较列排序的时候)

　　select top  * from UserLog where LogId > (select max(LogId) from (select top  LogId from UserLog order by LogId) a ) order by LogId

备注：这里max()函数也可以用于文本列，文本列的比较会根据字母顺序排列，数字 < 字母（无视大小写） < 中文字符

方法四：(row_number() over (order by LogId))

　　select top  * from ( select row_number() over (order by LogId) as rownumber,* from UserLog)awhere rownumber >  order by LogId

　　select * from (select row_number()over(order by LogId) as rownumber,* from UserLog)awhere rownumber >  and rownumber <  order by LogId

　　select * from (select row_number()over(order by LogId) as rownumber,* from UserLog)awhere rownumber between  and  order by LogId

　　select *from ( select row_number()over(order by tempColumn)rownumber,* from (select top  tempColumn=,* from UserLog where = order by LogId)a)bwhere rownumber>

今天无聊和朋友讨论分页，发现网上好多都是错的。网上经常查到的那个Top Not in 或者Max 大部分都不实用，很多都忽略了Order和性能问题。为此上网查了查，顺带把2000和2012版本的也补上了。

先说说网上常见SQL的错误或者说局限问题

select top 10 *

from table1

where id not in(

select top 开始的位置 id

from table1)

这样的确是可以取到分页数据，但是这是默认排序的，如果要按其中一列排序呢？那order by 加在哪里呢？里外都加，显然不行，外面的Order不起作用，只能嵌套，Oh my god,编程三个Select了，这效率。

为了好用效率高，总体思路还是老老实实的用RowNumber解决，但是SQL2000没有RowNumber，其实我们可以通过临时表自增列搞定，不多说，上例子。

SQL 2000 用临时表解决，通过在临时表中增加自增列解决RowNumber。

DECLARE @Start INT

DECLARE @End INT

SELECT @Start = 14000,@End = 14050

CREATE TABLE #employees (RowNumber INT IDENTITY(1,1),

LastName VARCHAR(100),FirstName VARCHAR(100),

EmailAddress VARCHAR(100))

INSERT INTO #employees (LastName, FirstName, EmailAddress)

SELECT LastName, FirstName, EmailAddress

FROM Employee

ORDER BY LastName, FirstName, EmailAddress

SELECT LastName, FirstName, EmailAddress

FROM #employees

WHERE RowNumber > @Start AND RowNumber <= @End

DROP TABLE #employees

GO

SQL 2005/2008 由于支持了Row_Number于是通过派生表的方式解决（两个嵌套）

DECLARE @Start INT

DECLARE @End INT

SELECT @Start = 14000,@End = 14050

SELECT LastName, FirstName, EmailAddress

FROM (SELECT LastName, FirstName, EmailAddress,

ROW_NUMBER() OVER (ORDER BY LastName, FirstName, EmailAddress) AS RowNumber

FROM Employee) EmployeePage

WHERE RowNumber > @Start AND RowNumber <= @End

ORDER BY LastName, FirstName, EmailAddress

GO

SQL 2005/2008 或者用CTE的方式实现，和派生表一样，就是好看点，执行计划都一样。

DECLARE @Start INT

DECLARE @End INT

SELECT @Start = 14000,@End = 14050;

WITH EmployeePage AS

(SELECT LastName, FirstName, EmailAddress,

ROW_NUMBER() OVER (ORDER BY LastName, FirstName, EmailAddress) AS RowNumber

FROM Employee)

SELECT LastName, FirstName, EmailAddress

FROM EmployeePage

WHERE RowNumber > @Start AND RowNumber <= @End

ORDER BY LastName, FirstName, EmailAddress

GO

ROW_NUMBER 比较好用的办法

--（1）在ROW_NUMBER的同时用COUNT计算总行数

declare @page_no int

declare @page_size int

set @page_no = 2

set @page_size = 10

;WITH tmp

AS

(

select *,

ROW_NUMBER() OVER(order by ID) num,

COUNT(*) OVER() total

from split_pages

)

select ID, Name

from tmp

where num BETWEEN (@page_size*(@page_no-1)+1) AND @page_size*@page_no

order by num

--（2）仅使用ROW_NUMBER计算总行数，IO最少

declare @page_no int

declare @page_size int

set @page_no = 2

set @page_size = 10

;with tmp

as

(

select *,

ROW_NUMBER() OVER(order by ID) num,

ROW_NUMBER() OVER(order by ID desc) num_desc

from split_pages

)

select ID, Name, num_desc + num -1 as total

from tmp

where num BETWEEN (@page_size*(@page_no-1)+1) AND @page_size*@page_no

order by num

SQL SERVER 2012 比较给力支持了OFFSET，于是一个Select结束战斗

SELECT LastName, FirstName, EmailAddress

FROM Employee

ORDER BY LastName, FirstName, EmailAddress

OFFSET 14000 ROWS

FETCH NEXT 50 ROWS ONLY;

最后说下，根据老外的文章，在2012里，如果前面加上TOP（50），那么执行计划就会少读很多行数据（读的精准了），提高性能。但是鉴于本人手头没2012也无法测试。至少在2008R2上加不加TOP执行计划都一样。

转自：https://www.cnblogs.com/ebread/p/SQLServer.html