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:

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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

SELECT
    top 1 *
FROM
    table_name
WHERE
    column_name IN (
        SELECT
            top N column_name
        FROM
            TABLE
        ORDER BY
            column_name
    )
ORDER BY
    column_name DESC

我写这个查询是为了求第n行。 使用此查询的示例如下

SELECT
    top 1 *
FROM
    Employee
WHERE
    emp_id IN (
        SELECT
            top 7 emp_id
        FROM
            Employee
        ORDER BY
            emp_id
    )
ORDER BY
    emp_id DESC

其他回答

Oracle:

select * from (select foo from bar order by foo) where ROWNUM = x

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。

SQL 2005及以上版本内置了这个特性。使用ROW_NUMBER()函数。它非常适合浏览<< Prev和Next >>样式的网页:

语法:

SELECT
    *
FROM
    (
        SELECT
            ROW_NUMBER () OVER (ORDER BY MyColumnToOrderBy) AS RowNum,
            *
        FROM
            Table_1
    ) sub
WHERE
    RowNum = 23
SELECT * FROM emp a
WHERE  n = ( 
    SELECT COUNT( _rowid)
    FROM emp b
    WHERE a. _rowid >= b. _rowid
);
SELECT
    top 1 *
FROM
    table_name
WHERE
    column_name IN (
        SELECT
            top N column_name
        FROM
            TABLE
        ORDER BY
            column_name
    )
ORDER BY
    column_name DESC

我写这个查询是为了求第n行。 使用此查询的示例如下

SELECT
    top 1 *
FROM
    Employee
WHERE
    emp_id IN (
        SELECT
            top 7 emp_id
        FROM
            Employee
        ORDER BY
            emp_id
    )
ORDER BY
    emp_id DESC