我感兴趣的是从数据库表中选择第n行的一些(理想的)数据库不可知的方法。看看如何使用以下数据库的本机功能来实现这一点也很有趣:
SQL Server MySQL PostgreSQL SQLite 甲骨文
我目前正在SQL Server 2005中做以下事情，但我有兴趣看到其他更不可知论的方法:
WITH Ordered AS (
SELECT ROW_NUMBER() OVER (ORDER BY OrderID) AS RowNumber, OrderID, OrderDate
FROM Orders)
SELECT *
FROM Ordered
WHERE RowNumber = 1000000
以上SQL: Firoz Ansari的Weblog的功劳
更新:参见Troels Arvin关于SQL标准的回答。Troels，你有我们可以引用的链接吗?
当前回答
从表中选择N个记录号
select * from
(select row_number() over (order by Rand() desc) as Rno,* from TableName) T where T.Rno = RecordNumber
Where RecordNumber --> Record Number to Select
TableName --> To be Replaced with your Table Name
例如，要从表Employee中选择第5条记录，您的查询应该是
select * from
(select row_number() over (order by Rand() desc) as Rno,* from Employee) T where T.Rno = 5
其他回答
select * from
(select * from ordered order by order_id limit 100) x order by
x.order_id desc limit 1;
首先按升序选择前100行，然后按降序选择最后一行并限制为1行。然而，这是一个非常昂贵的语句，因为它访问了两次数据。
这里有一个快速解决你困惑的方法。
SELECT * FROM table ORDER BY `id` DESC LIMIT N, 1
这里你可以通过填充N=0得到最后一行，通过填充N=1得到倒数第二行，通过填充N=3得到倒数第四行，等等。
这是面试中很常见的问题，也是一个很简单的回答。
如果你想要数量，ID或一些数字排序顺序，你可以在MySQL中使用CAST函数。
SELECT DISTINCT (`amount`)
FROM cart
ORDER BY CAST( `amount` AS SIGNED ) DESC
LIMIT 4 , 1
在这里，通过填写N = 4，您将能够从CART表中获得第五次最高金额记录。您可以匹配字段和表名并提出解决方案。
SQL SERVER
从顶部选择第n条记录
SELECT * FROM (
SELECT
ID, NAME, ROW_NUMBER() OVER(ORDER BY ID) AS ROW
FROM TABLE
) AS TMP
WHERE ROW = n
从底部选择第n条记录
SELECT * FROM (
SELECT
ID, NAME, ROW_NUMBER() OVER(ORDER BY ID DESC) AS ROW
FROM TABLE
) AS TMP
WHERE ROW = n
当我们在MSSQL 2000中工作时，我们做了所谓的“三重翻转”:
编辑
DECLARE @InnerPageSize int
DECLARE @OuterPageSize int
DECLARE @Count int
SELECT @Count = COUNT(<column>) FROM <TABLE>
SET @InnerPageSize = @PageNum * @PageSize
SET @OuterPageSize = @Count - ((@PageNum - 1) * @PageSize)
IF (@OuterPageSize < 0)
SET @OuterPageSize = 0
ELSE IF (@OuterPageSize > @PageSize)
SET @OuterPageSize = @PageSize
DECLARE @sql NVARCHAR(8000)
SET @sql = 'SELECT * FROM
(
SELECT TOP ' + CAST(@OuterPageSize AS nvarchar(5)) + ' * FROM
(
SELECT TOP ' + CAST(@InnerPageSize AS nvarchar(5)) + ' * FROM <TABLE> ORDER BY <column> ASC
) AS t1 ORDER BY <column> DESC
) AS t2 ORDER BY <column> ASC'
PRINT @sql
EXECUTE sp_executesql @sql
它并不优雅，速度也不快，但它奏效了。
下面是我最近为Oracle编写的一个sproc的通用版本，它允许动态分页/排序——HTH
-- p_LowerBound = first row # in the returned set; if second page of 10 rows,
-- this would be 11 (-1 for unbounded/not set)
-- p_UpperBound = last row # in the returned set; if second page of 10 rows,
-- this would be 20 (-1 for unbounded/not set)
OPEN o_Cursor FOR
SELECT * FROM (
SELECT
Column1,
Column2
rownum AS rn
FROM
(
SELECT
tbl.Column1,
tbl.column2
FROM MyTable tbl
WHERE
tbl.Column1 = p_PKParam OR
tbl.Column1 = -1
ORDER BY
DECODE(p_sortOrder, 'A', DECODE(p_sortColumn, 1, Column1, 'X'),'X'),
DECODE(p_sortOrder, 'D', DECODE(p_sortColumn, 1, Column1, 'X'),'X') DESC,
DECODE(p_sortOrder, 'A', DECODE(p_sortColumn, 2, Column2, sysdate),sysdate),
DECODE(p_sortOrder, 'D', DECODE(p_sortColumn, 2, Column2, sysdate),sysdate) DESC
))
WHERE
(rn >= p_lowerBound OR p_lowerBound = -1) AND
(rn <= p_upperBound OR p_upperBound = -1);
