SQL 分组后获取其中一个字段最大值的整条记录

--有id,name,createDate的一张表testTable
--根据name分组，获取每组中createDate最大的那条记录（整条）查询出来
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创建一张表，语句如下：

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CREATE TABLE [dbo].[testTable]

(

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

[name] [nchar] (10) COLLATE Chinese_PRC_CI_AS NULL,

[counts] [int] NULL,

[createDate] [datetime] NULL

)

GO

-- Constraints and Indexes

ALTER TABLE [dbo].[testTable] ADD CONSTRAINT [PK_testTable] PRIMARY KEY CLUSTERED ([id])

GO

插入测试数据：

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insert into testTable(id,name,counts,createDate) values(1,'A ',20,'01 14 2011 10:52PM')

insert into testTable(id,name,counts,createDate) values(2,'A ',10,'02 14 2011 10:52PM')

insert into testTable(id,name,counts,createDate) values(3,'B ',20,'03 14 2011 10:52PM')

insert into testTable(id,name,counts,createDate) values(4,'B ',40,'04 14 2011 10:52PM')

insert into testTable(id,name,counts,createDate) values(5,'B ',10,'05 14 2011 10:52PM')

insert into testTable(id,name,counts,createDate) values(6,'C ',20,'06 14 2011 10:52PM')

insert into testTable(id,name,counts,createDate) values(7,'C ',40,'07 14 2011 10:52PM')



查询SQL语句：

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select * from (

select id,name,counts,createDate,row_number() over(partition by name order by createDate desc) rn

from testTable

) t where t.rn <=1

结果如下：