作者OTZ (......囧)
看板Database
标题[SQL ] 请教语法的问题
时间Thu Aug 7 18:14:32 2008
资料表 tag_received
id , signal , time
c1 104 2008-08-06 17:48:29
c2 105 2008-08-06 17:48:30
c3 106 2008-08-06 17:48:30
c1 107 2008-08-06 17:48:32
c2 108 2008-08-06 17:48:33
c3 208 2008-08-06 17:48:35
c1 209 2008-08-06 17:48:38
c2 210 2008-08-06 17:48:40
c3 211 2008-08-06 17:48:42
c1 212 2008-08-06 17:48:43
想要取c1,c2,c3最新的资料出来
c1 212 2008-08-06 17:48:43
c2 210 2008-08-06 17:48:40
c3 211 2008-08-06 17:48:42
用的语法是
SELECT id, signal, max(time)time FROM tag_received GROUP BY id;
出来的时间是最新的没错, 但是 signal 却是第一笔的数值
c1 104 2008-08-06 17:48:43 << 时间是最新的 , 但是 signal 却是最旧一笔
c2 105 2008-08-06 17:48:40
c3 106 2008-08-06 17:48:42
请问是用的语法错误 , 还是有什麽没注意到的地方呢 ? 谢谢
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◆ From: 61.62.14.159
※ 编辑: OTZ 来自: 61.62.14.159 (08/07 18:16)
1F：推 slalala:你下的语法跟'想要取c1,c2,c3最新的资料出来'没什麽关联耶 08/07 19:16