对数据按组排序

数据库环境：SQL SERVER 2005

　　有数据如图1，字段id是序号，id相同的为一组，createtime为创建时间。要求：

将createtime为最新时间所在的组排在前面，同时，同一组内的数据按createtime降序排序。

最终结果如图2所示

       

　　实现思路：

　　1.用分析函数取组内最大值

　　2.按照组内最新时间和创建时间降序排序

　　SQL实现：

/*测试数据*/
WITH    x0
          AS ( SELECT   1 AS id ,
                        100 AS data ,
                        CONVERT(DATETIME, '2015-09-01 12:23:56') AS createtime
               UNION ALL
               SELECT   1 AS id ,
                        24 AS data ,
                        CONVERT(DATETIME, '2015-09-02 18:25:26') AS createtime
               UNION ALL
               SELECT   2 AS id ,
                        68 AS data ,
                        CONVERT(DATETIME, '2015-09-01 08:46:12') AS createtime
               UNION ALL
               SELECT   2 AS id ,
                        360 AS data ,
                        CONVERT(DATETIME, '2015-09-01 00:52:58') AS createtime
               UNION ALL
               SELECT   2 AS id ,
                        200 AS data ,
                        CONVERT(DATETIME, '2015-09-03 10:08:36') AS createtime
               UNION ALL
               SELECT   3 AS id ,
                        70 AS data ,
                        CONVERT(DATETIME, '2015-09-02 13:48:12') AS createtime
               UNION ALL
               SELECT   4 AS id ,
                        108 AS data ,
                        CONVERT(DATETIME, '2015-08-31 03:11:23')
             ),/*分析函数求组内最新时间*/
        x1
          AS ( SELECT   id ,
                        data ,
                        createtime ,
                        MAX(createtime) OVER ( PARTITION BY id ) AS createtime_max
               FROM     x0
             )/*对结果集排序*/
    SELECT  id ,
            data ,
            createtime
    FROM    x1
    ORDER BY createtime_max DESC ,
            createtime DESC
            

(本文完)