如何使用mysql查询每个用户一次操作时记录的值

Question

数据如下：

==============================
 user        time        num
------------------------------
  a       1479101865      3
------------------------------
  b       1479101866      2
------------------------------
  a       1479101866      1
------------------------------
  a       1479101867      5
------------------------------
  b       1479101868      1
------------------------------
  c       1479101868      7
==============================

请问以时间为单位，如何查每个用户第一次记录的num？

Answer 1

按时间顺序排序后分组查询

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