問題描述

數(shù)據(jù)如下：

============================== usertimenum------------------------------ a 1479101865 3------------------------------ b 1479101866 2------------------------------ a 1479101866 1------------------------------ a 1479101867 5------------------------------ b 1479101868 1------------------------------ c 1479101868 7==============================

請問以時間為單位，如何查每個用戶第一次記錄的num？

問題解答

按時間順序排序后分組查詢

select user,num from (select * from tb order by time asc) as a group by a.user;