Sql 如何找到val1的最大值，其中val2是最大值？

Sybase数据库管理系统

在我的玩家表中，我有4列：

玩家

得分

邮政署

加上

如果我想找到玩家的分数，其中post_dt是最大值，add_dt是post_dt和该玩家的最大值，我该怎么做？我下面的查询需要很长时间才能运行，可能效率不高

select player, score from tb t1 
where post_dt in 
      (select max(add_dt) 
       from tb t2 
       where t1.player = t2.player and t2.post_dt in 
             (select max(post_dt) 
              from tb t2 
              where t1.player = t2.player))

桌子

查询的预期结果：

01, 26, 2017-02-01, 2017-01-17
02, 27, 2017-03-25, 2017-03-05
03,  4, 2017-01-03, 2016-12-25

---

可以通过使用相关子查询来实现这一点

SELECT t1.player,
       t1.score
       FROM tb t1
       WHERE t1.post_dt = (SELECT max(t2.post_dt)
                                  FROM tb t2
                                  WHERE t2.player = t1.player)
             AND t1.add_dt = (SELECT max(t2.add_dt)
                                     FROM tb t2
                                     WHERE t2.player = t1.player
                                           AND t2.post_dt = t1.post_dt);

或者，如果DBMS支持窗口函数，请使用

rank（）

window函数

SELECT x.player,
       x.score
       FROM (SELECT t.player,
                    t.score,
                    rank() OVER (PARTITION BY t.player
                                 ORDER BY t.post_dt DESC,
                                          t.add_dt DESC) r
                    FROM tb t) x
       WHERE x.r = 1;

还有一种选择是内部连接子查询，它分别通过

player

或

player

和

post\dt

构建最大值

SELECT t1.player,
       t1.score
       FROM tb t1
            INNER JOIN (SELECT t2.player,
                               max(t2.post_dt) post_dt
                               FROM tb t2
                               GROUP BY t2.player) t3
                       ON t3.player = t1.player
                          AND t3.post_dt = t1.post_dt
            INNER JOIN (SELECT t3.player,
                               t3.post_dt,
                               max(t3.add_dt) add_dt
                               FROM tb t3
                               GROUP BY t3.player,
                                        t3.post_dt) t4
                       ON t4.player = t1.player
                          AND t4.post_dt = t1.post_dt
                          AND t4.add_dt = t1.add_dt;

---

你的数据库管理系统是什么？你能详细说明一下吗，最好是用一些示例数据。很难理解您的需求。哪种Sybase RDBMS产品（ASE？SQLAnywhere？IQ？Advantage？）和版本？除了Cetin的评论，请阅读，然后回来更新你的问题。我用样本数据更新了我的帖子。这太棒了！非常感谢。我用了你的第二个解决方案。

SELECT t1.player,
       t1.score
       FROM tb t1
            INNER JOIN (SELECT t2.player,
                               max(t2.post_dt) post_dt
                               FROM tb t2
                               GROUP BY t2.player) t3
                       ON t3.player = t1.player
                          AND t3.post_dt = t1.post_dt
            INNER JOIN (SELECT t3.player,
                               t3.post_dt,
                               max(t3.add_dt) add_dt
                               FROM tb t3
                               GROUP BY t3.player,
                                        t3.post_dt) t4
                       ON t4.player = t1.player
                          AND t4.post_dt = t1.post_dt
                          AND t4.add_dt = t1.add_dt;