我在带有日期戳的表中记录了用户操作.
每次用户进入项目时,都会记录他们查看该项目并标记日期时间.
我想获得用户最后进入的TOP 20项目.
这是我到目前为止:
SELECT DISTINCT TOP (20) Users_Tran_ID
FROM App_UserLog
WHERE (Users_ID = 'ADMIN') AND (Users_Transaction LIKE 'Permit Viewed%')
ORDER BY App_UserLog.Users_LogDate DESC
问题是,我不想在输出中使用Users_LogDate,因为我需要UNIQUE Users_Tran_ID.
当我从SELECT中删除Users_LogDate时,我收到以下错误:
ORDER BY items must appear in the select list if SELECT DISTINCT is specified.
这是我得到的基本选择和结果集.我只想要不同的Users_Tran_ID,只需要TOP 20.
ADMIN Permit Viewed B2011-0012 2013-08-29 17:35:04.000
ADMIN Permit Viewed B2011-0012 2013-08-29 17:29:09.000
ADMIN Permit Viewed B2006-0043 2013-08-29 17:29:05.000
ADMIN Permit Viewed B2011-0012 2013-08-29 17:28:49.000
ADMIN Permit Viewed B2008-0167 2013-08-29 17:17:13.000
ADMIN Permit Viewed B2006-0043 2013-08-29 17:17:08.000
ADMIN Permit Viewed B2011-0012 2013-08-29 17:16:55.000
ADMIN Permit Viewed B2011-0012 2013-08-29 17:16:45.000
ADMIN Permit Viewed B2011-0012 2013-08-29 17:16:38.000
ADMIN Permit Viewed B2007-0478 2013-08-29 17:16:32.000
ADMIN Permit Viewed B2011-0012 2013-08-29 11:39:59.000
ADMIN Permit Viewed B2007-0478 2013-08-29 11:22:05.000
ADMIN Permit Viewed B2007-0478 2013-08-29 11:22:03.000
ADMIN Permit Viewed B2011-0012 2013-08-29 10:23:17.000
ADMIN Permit Viewed B2011-0012 2013-08-29 10:21:58.000
ADMIN Permit Viewed B2011-0012 2013-08-29 10:20:41.000
ADMIN Permit Viewed B2011-0012 2013-08-29 10:20:37.000
ADMIN Permit Viewed B2007-0478 2013-08-29 10:18:01.000
ADMIN Permit Viewed B2007-0478 2013-08-29 10:17:58.000
ADMIN Permit Viewed B2011-0012 2013-08-29 10:17:54.000
ADMIN Permit Viewed B2011-0012 2013-08-29 10:01:50.000
ADMIN Permit Viewed B2011-0012 2013-08-29 10:01:48.000
ADMIN Permit Viewed B2007-0478 2013-08-29 09:56:32.000
ADMIN Permit Viewed B2007-0478 2013-08-29 09:53:31.000
ADMIN Permit Viewed B2007-0478 2013-08-29 09:53:27.000
ADMIN Permit Viewed ENG2012-0141 2013-08-15 12:51:09.000
ADMIN Permit Viewed ENG2012-0141 2013-08-15 12:51:07.000
ADMIN Permit Viewed BLD2012-0094 2013-08-13 12:01:39.000
ADMIN Permit Viewed ENG2013-0047 2013-08-05 10:40:34.000
ADMIN Permit Viewed ENG2013-0047 2013-08-05 10:40:28.000
ADMIN Permit Viewed ENG2013-0047 2013-08-05 10:40:24.000
ADMIN Permit Viewed ENG2013-0047 2013-08-05 10:40:21.000
ADMIN Permit Viewed ENG2013-0047 2013-08-05 10:40:13.000
ADMIN Permit Viewed ENG2013-0047 2013-08-05 10:40:09.000
ADMIN Permit Viewed ENG2013-0047 2013-08-05 10:40:07.000
ADMIN Permit Viewed ENG2012-0141 2013-08-05 10:37:55.000
ADMIN Permit Viewed ENG2012-0141 2013-08-05 10:37:50.000
ADMIN Permit Viewed ENG2012-0141 2013-08-05 10:37:46.000
ADMIN Permit Viewed ENG2012-0141 2013-08-05 10:37:40.000
ADMIN Permit Viewed ENG2012-0141 2013-08-05 10:37:33.000
ADMIN Permit Viewed ENG2012-0141 2013-08-05 10:37:31.000
ADMIN Permit Viewed BLD2012-0919 2013-08-05 10:27:21.000
ADMIN Permit Viewed BLD2012-0919 2013-08-05 10:27:17.000
ADMIN Permit Viewed ENG2012-0119 2013-08-05 10:26:51.000
ADMIN Permit Viewed ENG2012-0119 2013-08-05 10:26:48.000
我怎样才能做到这一点？
你想使用group by而不是distinct:
SELECT TOP (20) Users_Tran_ID
FROM App_UserLog
WHERE (Users_ID = 'ADMIN') AND (Users_Transaction LIKE 'Permit Viewed%')
GROUP BY Users_Tran_ID
ORDER BY max(App_UserLog.Users_LogDate) DESC;
通过聚合,您可以指定要按最新的logdate排序.瞧,那应该做你想要的.