sql 中 limit 与 limit，offset连用

Posted 2021-01-06 Maggie1010

编写一个 SQL 查询，获取 Employee 表中第 n 高的薪水（Salary）。

+----+--------+
| Id | Salary |
+----+--------+
| 1  | 100    |
| 2  | 200    |
| 3  | 300    |
+----+--------+

例如上述 Employee 表，n = 2 时，应返回第二高的薪水 200。如果不存在第 n 高的薪水，那么查询应返回 null。

+------------------------+
| getNthHighestSalary(2) |
+------------------------+
| 200                    |
+------------------------+

CREATE FUNCTION getNthHighestSalary(N INT) RETURNS INT
BEGIN
declare m int;
SET m = N - 1;
  RETURN (
      # Write your mysql query statement below.
          SELECT
            (
                SELECT DISTINCT
                    Salary
                FROM
                    employee
                ORDER BY
                    Salary DESC
                LIMIT m,1
            ) AS getNthHighestSalary
    
  );
END

SELECT * FROM employee ORDER BY Salary ASC LIMIT 3,2;

从当前的第三个之后的第四位开始往后数两位

SELECT * FROM employee ORDER BY Salary ASC LIMIT 2 OFFSET 3;

从当前数据中选取2个，从第三位往后数，就是第四位开始