取出分组后每组的第一条记录（不用group by）按时间排序

--操作日志表
CREATE TABLE [dbo].[JobLog](

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

[FunctionId] [nvarchar](20) NULL,

[OperateTime] [datetime]
NULL,

CONSTRAINT [PK_JobLog]
PRIMARY KEY CLUSTERED

(

[JobLogId] ASC

)WITH (PAD_INDEX  = OFF, STATISTICS_NORECOMPUTE  = OFF, IGNORE_DUP_KEY = OFF, ALLOW_ROW_LOCKS 
= ON, ALLOW_PAGE_LOCKS  = ON) ON [PRIMARY]

) ON [PRIMARY]

GO

-- 操作日志表的所有记录
select *
from JobLog

查询结果：
1    001    2007-11-01
2    001    2007-11-02
3    001    2007-11-03
4    002    2007-11-04
5    002    2007-11-05
6    003    2007-11-06
7    004    2007-11-07
8    004    2007-11-08
9    005    2007-11-09
10  005    2007-11-10

-- 每个功能最后一次操作记录
SELECT * FROM JobLog A

WHERE JobLogId in

(SELECT TOP
1 JobLogId FROM
JobLog WHERE A.FunctionId = FunctionId ORDER BY OperateTime DESC)

查询结果：
3    001    2007-11-03
5    002    2007-11-05
6    003    2007-11-06
8    004    2007-11-08
10  005    2007-11-10