Question

类似于this question，我在MySQL 8.0.15中具有下表：

CREATE TABLE golf_scores (id INT PRIMARY KEY AUTO_INCREMENT, person TEXT, score INT, age INT);
INSERT INTO golf_scores (person, score, age) VALUES ('Angela', 40, 25),('Angela', 45, 25),('Angela', 55, 25),('Peter',45, 32),('Peter',55,32),('Rachel', 65, 35),('Rachel',75,35),('Jeff',75, 16);
SELECT * FROM golf_scores;
+----+--------+-------+------+
| id | person | score | age  |
+----+--------+-------+------+
|  1 | Angela |    40 |   25 |
|  2 | Angela |    45 |   25 |
|  3 | Angela |    55 |   25 |
|  4 | Peter  |    45 |   32 |
|  5 | Peter  |    55 |   32 |
|  6 | Rachel |    65 |   35 |
|  7 | Rachel |    75 |   35 |
|  8 | Jeff   |    75 |   16 |
+----+--------+-------+------+

我们要选择以下“最佳” 3行：

+----+--------+-------+------+
| id | person | score | age  |
+----+--------+-------+------+
|  1 | Angela |    40 |   25 |
|  4 | Peter  |    45 |   32 |
|  6 | Rachel |    65 |   35 |
+----+--------+-------+------+

换句话说，最低的3个高尔夫得分没有人，以及该行的其他列的重复。我不担心关系。我仍然只想要三个结果。

查询SELECT person, MIN(score) as min_score FROM golf_scores GROUP BY person ORDER BY min_score LIMIT 3;给出了正确的行，但仅限于列person和score`。当我尝试像这样修改它时：

SELECT id, person, MIN(score) as min_score, age FROM golf_scores GROUP BY person ORDER BY min_score LIMIT 3;

我收到此错误：

错误1055（42000）：SELECT列表的表达式＃1不在GROUP BY子句中，并且包含未聚合的列'records.golf_scores.id'，该列在功能上不依赖于GROUP BY子句中的列；这与sql_mode = only_full_group_by
不兼容

我还尝试使用SELECT id, DISTINCT person, score, age FROM golf_scores ORDER BY score LIMIT 3消除重复的名称，但出现错误

错误1064（42000）：您的SQL语法有错误；检查与您的MySQL服务器版本相对应的手册以获取正确的语法，以在第1行“ DISTINCT人，从golf_scores ORDER BY得分极限3”附近得分

如何在MySQL中获得所需的输出？

Answer 1

使用row_number()：

select t.*
from (select t.*, row_number() over (partition by person order by score) as seqnum
      from golf_scores  t
     ) t
where seqnum = 1
order by score asc
limit 3;

在旧版本中，您可以通过使用相关子查询和id来做到这一点：

select gs.*
from golf_scores gs
where gs.id = (select gs2.id
               from golf_scores gs2
               where gs2.person = gs.person
               order by gs2.score asc
               limit 1
              )
order by score asc
limit 3;

这也许也是在golf_scores(person, score, id)上建立索引的最快方法。

Answer 2

这是一种方法：

SELECT x.* 
  FROM golf_scores x
  JOIN 
     ( SELECT MIN(id) id FROM
            ( SELECT a.* 
                FROM golf_scores a 
                JOIN 
                   ( SELECT person, MIN(score) score FROM golf_scores GROUP BY person ) b 
                  ON b.person = a.person 
                 AND b.score = a.score 
            ) n
        GROUP
           BY person
            , score 
     ) y
    ON y.id = x.id
 ORDER 
    BY x.score LIMIT 3;

在MySQL 8中按类别显示前N行，而在另一类别中不显示重复行

2 个答案: