SQL 如何先排序后分组

[MUGOER]

task 表(任务表)
ID type level url createtime

1 1 1 http://asf.com 2019-09-18 14:45:36
2 1 1 http://asfaf.com 2019-09-18 14:45:40

plan 表(任务详情表)
ID taskid userid state createtime

1 1 1 1 0 2019-09-18 14:45:50
2 2 1 1 0 2019-09-18 14:45:58


user 表(客户表)
ID username password usernick

1 admin 123456 测试
2 root 123456 管理员

SELECT *  FROM task inner join plan ON task.id = plan.taskid
                                   inner join user ON plan.userid = user.id
WHERE
 task.level = 1
GROUP BY plan.userid

业务想要统计结果只取一条 userid 为 1 的，结果是 task.createtime 以时间最早的优先出来

现在统计出来的结果是task.createtime 时间 2019-09-18 14:45:40 优先出来了， 2019-09-18 14:45:36 最后的先出来，

请问如何才能优先取出 2019-09-18 14:45:36 的而不是 2019-09-18 14:45:40

谢谢各位前辈

[文盲老顾]

min(createtime),max(createtime) count,sum,min,max,avg了解下？

[RINK_1]

SELECT *
FROM 
(SELECT *,ROW_NUMBER() OVER (PARTITION BY USER.ID ORDER BY task.createtime)  AS SEQ
FROM task 
inner join plan ON task.id = plan.taskid
inner join user ON plan.userid = user.id
WHERE LEVEL=1
AND USER.ID=1) AS A
WHERE SEQ=1

[二月十六]

SELECT *
  FROM (   SELECT plan.ID,taskid,userid,state,plan.createtime AS pcreatetime,task.ID AS tid,type,level,url,task.createtime,user.ID AS uid,username,password,usernick
                  ,ROW_NUMBER() OVER (PARTITION BY plan.userid ORDER BY task.createtime) rn
             FROM task
            INNER JOIN plan
               ON task.ID     = plan.taskid
            INNER JOIN user
               ON plan.userid = user.ID
            WHERE task.level = 1) t
 WHERE rn = 1;

[MUGOER]

引用 1 楼 文盲老顾 的回复:

min(createtime),max(createtime) count,sum,min,max,avg了解下？

感谢回复！

[MUGOER]

引用 2 楼 RINK_1 的回复:

SELECT *
FROM 
(SELECT *,ROW_NUMBER() OVER (PARTITION BY USER.ID ORDER BY task.createtime)  AS SEQ
FROM task 
inner join plan ON task.id = plan.taskid
inner join user ON plan.userid = user.id
WHERE LEVEL=1
AND USER.ID=1) AS A
WHERE SEQ=1

感谢回复！

[MUGOER]

引用 3 楼 二月十六 的回复:

SELECT *
  FROM (   SELECT plan.ID,taskid,userid,state,plan.createtime AS pcreatetime,task.ID AS tid,type,level,url,task.createtime,user.ID AS uid,username,password,usernick
                  ,ROW_NUMBER() OVER (PARTITION BY plan.userid ORDER BY task.createtime) rn
             FROM task
            INNER JOIN plan
               ON task.ID     = plan.taskid
            INNER JOIN user
               ON plan.userid = user.ID
            WHERE task.level = 1) t
 WHERE rn = 1;

感谢回复，已测试通过，再次感谢！