Question

我正在尝试根据SQL Server 2008中特定列值的最大值选择行。我需要根据最大版本选择书名和年份。

当前表格数据：

    BookName    Year    Edition
Latest Science  2013    1
Latest Science  2014    2
Latest Science  2015    3
Easy Maths      2014    1
Easy Maths      2015    2
Magic vs Logic  2015    1

输出应为：

BookName    Year    Edition
Latest Science  2015    3
Easy Maths      2015    2
Magic vs Logics 2015    1

我试过了，但只产生了整行的一行

SELECT     Book, year, edition
FROM         Book_info
where edition=(select max(edition) from book_info)

Answer 1

我会这样做：

;WITH cte AS (
 SELECT *, 
 ROW_NUMBER() OVER (PARTITION BY BookName ORDER BY Edition DESC) AS rn
 FROM book_info
)
SELECT * FROM cte
WHERE rn=1

Answer 2

你应该通过有条款来查找分组。

以下是符合您要求的整个脚本，它会返回您正在寻找的结果。

USE [Test]

--table

SET ANSI_NULLS ON

GO

SET QUOTED_IDENTIFIER ON

GO

SET ANSI_PADDING ON

GO

CREATE TABLE [dbo].[Book](

[Id] [int] IDENTITY(1,1) NOT NULL,

[BookName] [varchar](50) NOT NULL,

[Year] [int] NOT NULL,

[Edition] [int] NOT NULL

) ON [PRIMARY]

GO

SET ANSI_PADDING OFF

GO



USE [Test]

GO

--records

INSERT INTO [dbo].[Book]

([BookName]

,[Year]

,[Edition])

VALUES

('Last Science', 2013 ,1),

('Last Science', 2014 ,2),

('Last Science', 2015 ,3),

('Easy Maths', 2014 ,1),

('Easy Maths', 2015 ,2),

('Magic vs Logic', 2015 ,1)

GO

USE [Test]

GO

--query

SELECT

BookName,

MAX([Year]) AS Year,

MAX(Edition) AS Edition

FROM dbo.Book

GROUP BY

BookName

Order by MAX(Edition) DESC

如何根据特定列的最大值选择行？

2 个答案: