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
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select top 10 *
from table1
where id not in(
select top 开始的位置 id
from table1)
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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。
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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
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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）
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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
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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。
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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
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SQL SERVER 2012 比较给力支持了OFFSET，于是一个Select结束战斗
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SELECT LastName, FirstName, EmailAddress
FROM Employee
FETCH NEXT 50 ROWS ONLY; ORDER BY LastName, FirstName, EmailAddress
OFFSET 14000 ROWS
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Oracle分页
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select * from (
select rownum as rn, source.* from (
select * from (表名称)
) source where rownum <= 5) result where rn >= 1 order by(排序列名) asc; |
方法二 使用Between 推荐
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select * from
(select a.*,rownum rn from
(select * from 表名称) a
)
where rn between 起始 and 结束 order by(排序列名) |
