如何從結果中獲取最新的行？

Question

我有這個疑問

SELECT ann_arr.id,ann_arr.user_id,ann_arr.date,ann_arr.time, 
ann_arr.venue_id 
FROM ann_arr 
WHERE user_id 
IN (SELECT DISTINCT n2.mem_id AS frnd FROM network n1,network n2 WHERE n1.frd_id=n2.mem_id AND n1.mem_id='329' AND n2.frd_id='329') 
AND ann_arr.user_id !='329' 
ORDER BY DATE DESC,TIME DESC 

我得到的結果

id user_id date time venue_id 
995 399 2012-02-02 12:37:30 56 
994 399 2012-02-02 12:36:06 56 
993 399 2012-02-02 12:35:15 56 
992 399 2012-02-02 12:32:40 56 
991 399 2012-02-02 12:26:17 56 
990 399 2012-02-02 12:23:06 56 
989 399 2012-02-02 12:21:52 56 
968 693 2012-01-25 13:27:11 1016 

我想要的結果必須包含的最後id像用戶唯一的用戶ID是什麼399 ID將955

*備註 SELECT DISTINCT n2.mem_id AS frnd FROM network n1,network n2 WHERE n1.frd_id=n2.mem_id AND n1.mem_id='329' AND n2.frd_id='329'將包含用戶朋友ID說'399','693'等

//預期的答案

id user_id date time venue_id 
995 399 2012-02-02 12:37:30 56 
968 693 2012-01-25 13:27:11 1016 

請幫助

感謝

Answer 1

你應該在集團給一個嘗試通過USER_ID，日期&切換順序。

Answer 2

ID DESC添加到您的ORDER BY子句。

Answer 3

如果我已經corretly明白，你需要按USER_ID：

SELECT ann_arr.id,ann_arr.user_id,ann_arr.date,ann_arr.time, 
ann_arr.venue_id 
FROM ann_arr 
WHERE user_id 
IN (SELECT DISTINCT n2.mem_id AS frnd FROM network n1,network n2 WHERE n1.frd_id=n2.mem_id AND n1.mem_id='329' AND n2.frd_id='329') 
AND ann_arr.user_id !='329' 
GROUP BY ann_arr.user_id 
ORDER BY DATE DESC,TIME DESC