mysql 分組查詢每組的最新一條資料

1.原始資料

學生成績表

2.想要獲取每個考生最新的考試成績，網上的例子

select a.* from (select * from scoreinfo order by scoreinfo.createtime desc ) as a

group by a.snum

order by a.createtime;

很明顯執行結果不對，通過網上查詢發現

mysql5.7時，子查詢的排序已經變為無效了

select a.* from (select * from scoreinfo order by scoreinfo.createtime desc limit 1000) as a

group by a.snum

order by a.createtime;

方法2

select * from scoreinfo

join (select snum, max(createtime) as createtime from scoreinfo group by scoreinfo.snum) as a

where scoreinfo.snum=a.snum&&scoreinfo.createtime=a.createtime;

參考：

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