Mysql 限制，但添加了更多行

Question

我有这张桌子：

name   | age
John   | 35
Amanda | 34
Jane   | 34
Jack   | 34
Craig  | 32
Jason  | 32
Phil   | 32
Kris   | 32
Tyler  | 25
Harry  | 25
Duke   | 24

我想按年龄 desc 排序并选择前五行。但如果有更多与第 5 行相同年龄的人，我也希望他们出现在我的结果中。类似于：(SELECT * FROM people ORDER BY age DESC LIMIT 0, 5 as W) UNION (SELECT * FROM people WHERE age = W[4].age)

所以上面例子的结果是：

John   | 35
Amanda | 34
Jane   | 34
Jack   | 34
Craig  | 32
Jason  | 32
Phil   | 32
Kris   | 32

• 约翰、阿曼达、简、杰克、克雷格在结果中，因为有前五个最老的
• Jason、Phil、Kris 出现在结果中，因为他们与第五排的年龄相同

有什么办法吗？非常感谢

Answer 1

DROP TABLE IF EXISTS my_table;

CREATE TABLE my_table
(name VARCHAR(12) NOT NULL PRIMARY KEY
,age INT NOT NULL)
;

INSERT INTO my_table VALUES
('John'   ,35),
('Amanda' ,34),
('Jane'   ,34),
('Jack'   ,34),
('Craig'  ,32),
('Jason'  ,32),
('Phil'   ,32),
('Kris'   ,32),
('Tyler'  ,25),
('Harry'  ,25),
('Duke'   ,24);

SELECT DISTINCT y.*
           FROM
              ( SELECT *
                  FROM my_table
                 ORDER
                    BY age DESC
                 LIMIT 5
              ) x
           JOIN my_table y
             ON y.age = x.age;
+--------+-----+
| name   | age |
+--------+-----+
| John   |  35 |
| Amanda |  34 |
| Jane   |  34 |
| Jack   |  34 |
| Craig  |  32 |
| Jason  |  32 |
| Phil   |  32 |
| Kris   |  32 |
+--------+-----+

SQL DEMO

Answer 2

如果你尝试一下会怎样

SELECT * FROM people
WHERE Age IN (SELECT DISTINCT Age FROM people ORDER BY Age DESC LIMIT 5)

Answer 3

您必须使用内部查询来选择前 5 个年龄，然后倒序选择最后一个。

使用Limit 4, 1跳过前4个并选择最后一个

SQL DEMO

SELECT *
FROM (SELECT * 
      FROM people 
      ORDER BY age DESC 
      LIMIT 5 ) as w
UNION 
SELECT * 
FROM people 
WHERE age = (SELECT age
             FROM Table1
             ORDER BY `age` DESC
             LIMIT 4, 1)

输出