如何找到MySQL列的第n个最高值?
要查找列的第n个最大值,您需要将ORDERBYDESC与LIMIT子句一起使用。如果要列的第二高值,请使用以下语法:
SELECT *FROM yourTableName ORDER BY DESC yourColumnName LIMIT 1,1;
如果您希望列的第四高值,请使用以下语法:
SELECT *FROM yourTableName ORDER BY DESC yourColumnName LIMIT 3,1;
如果要获取列的第一个最大值,请使用以下语法:
SELECT *FROM yourTableName ORDER BY DESC yourColumnName LIMIT 1;
如以上语法中,您只需要在LIMIT子句中进行更改。为了理解上述语法,让我们创建一个表。创建表的查询如下:
mysql> create table NthSalaryDemo -> ( -> Id int NOT NULL AUTO_INCREMENT, -> Name varchar(10), -> Salary int, -> PRIMARY KEY(Id) -> );
使用insert命令在表中插入一些记录。查询如下:
mysql> insert into NthSalaryDemo(Name,Salary) values('Larry',5700); mysql> insert into NthSalaryDemo(Name,Salary) values('Sam',6000); mysql> insert into NthSalaryDemo(Name,Salary) values('Mike',5800); mysql> insert into NthSalaryDemo(Name,Salary) values('Carol',4500); mysql> insert into NthSalaryDemo(Name,Salary) values('Bob',4900); mysql> insert into NthSalaryDemo(Name,Salary) values('David',5400); mysql> insert into NthSalaryDemo(Name,Salary) values('Maxwell',5300); mysql> insert into NthSalaryDemo(Name,Salary) values('James',4000); mysql> insert into NthSalaryDemo(Name,Salary) values('Robert',4600);
使用select语句显示表中的所有记录。查询如下:
mysql> select *from NthSalaryDemo;
以下是输出:
+----+---------+--------+ | Id | Name | Salary | +----+---------+--------+ | 1 | Larry | 5700 | | 2 | Sam | 6000 | | 3 | Mike | 5800 | | 4 | Carol | 4500 | | 5 | Bob | 4900 | | 6 | David | 5400 | | 7 | Maxwell | 5300 | | 8 | James | 4000 | | 9 | Robert | 4600 | +----+---------+--------+ 9 rows in set (0.00 sec)
情况1:这是获取列的第n个最大值的查询。
以下查询将给出“薪水”列的第四高值:
mysql> select *from NthSalaryDemo order by Salary desc limit 3,1;
以下是输出:
+----+-------+--------+ | Id | Name | Salary | +----+-------+--------+ | 6 | David | 5400 | +----+-------+--------+ 1 row in set (0.00 sec)
情况2:这是获取列“Salary”的第二个最大值的查询:
mysql> select *from NthSalaryDemo order by Salary desc limit 1,1;
以下是输出:
+----+------+--------+ | Id | Name | Salary | +----+------+--------+ | 3 | Mike | 5800 | +----+------+--------+ 1 row in set (0.00 sec)
情况3: 这是获取列的第一个最大值的查询:
mysql> select *from NthSalaryDemo order by Salary desc limit 1;
以下是输出:
+----+------+--------+ | Id | Name | Salary | +----+------+--------+ | 2 | Sam | 6000 | +----+------+--------+ 1 row in set (0.00 sec)
情况4:如果要获取“薪水”列的第8个最高值,请使用以下查询:
mysql> select *from NthSalaryDemo order by Salary desc limit 7,1;
以下是输出:
+----+-------+--------+ | Id | Name | Salary | +----+-------+--------+ | 4 | Carol | 4500 | +----+-------+--------+ 1 row in set (0.00 sec)