---------------------------| from | to | text | time |---------------------------| seg | me | ye! | 4 |---------------------------| seg | me | ye! | 3 |---------------------------| seg | yu | ye! | 2 |---------------------------| seg | yu | ye! | 1 |---------------------------大概是這個(gè)樣子的一個(gè)表，我想知道能不能用一條語(yǔ)句提取出from=seg下所有不同的to字段值的time最新的一條數(shù)據(jù)，如果不能一句話的話寫成幾句也成0_0，比如上面應(yīng)該獲取到---------------------------| from | to | text | time |---------------------------| seg | me | ye! | 4 |---------------------------| seg | yu | ye! | 2 |---------------------------這兩條數(shù)據(jù)。
2 回答
慕田峪9158850
TA貢獻(xiàn)1794條經(jīng)驗(yàn) 獲得超8個(gè)贊
使用group by 匯總即可
select t.* from t , ( select c_from,c_to,max(c_time ) as c_time from t where c_from = 'seg' group by c_from,c_to ) t1where t.c_from = t1.c_from and t.c_to = t1.c_toand t.c_time = t1.c_time
明月笑刀無(wú)情
TA貢獻(xiàn)1828條經(jīng)驗(yàn) 獲得超4個(gè)贊
SELECT a.* FROM user_post a, ( SELECT content, MAX (post_date) post_date FROM user_post WHERE user_name = 'withrock' GROUP BY content) b WHERE a.content = b.content AND a.post_date = b.post_date
這張表的結(jié)構(gòu)和你的不太一樣，不過(guò)描述的問(wèn)題是一樣的.
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