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法律研究找出 MySQL 員工表的最高薪水和第二高薪水
可以使用 LIMIT OFFSET 來從員工表獲取最高工資和第二高的工資。語法如下所述 -
SELECT yourColumnName1,yourColumnName2,....N from yourTableName ORDER BY yourColumnName desc limit 2 offset 0;
為了理解上述語法，讓我們建立一個表。建立表的查詢如下所示 -
mysql> create table EmployeeMaxAndSecondMaxSalary -> ( -> EmployeeId int, -> Employeename varchar(20), -> EmployeeSalary int -> ); Query OK, 0 rows affected (0.88 sec)
使用 insert 命令向表中插入一些記錄 -
mysql> insert into EmployeeMaxAndSecondMaxSalary values(1,'John',34566); Query OK, 1 row affected (0.20 sec) mysql> insert into EmployeeMaxAndSecondMaxSalary values(2,'Bob',56789); Query OK, 1 row affected (0.17 sec) mysql> insert into EmployeeMaxAndSecondMaxSalary values(3,'Carol',44560); Query OK, 1 row affected (0.26 sec) mysql> insert into EmployeeMaxAndSecondMaxSalary values(4,'Sam',76456); Query OK, 1 row affected (0.29 sec) mysql> insert into EmployeeMaxAndSecondMaxSalary values(5,'Mike',65566); Query OK, 1 row affected (0.14 sec) mysql> insert into EmployeeMaxAndSecondMaxSalary values(6,'David',89990); Query OK, 1 row affected (0.19 sec) mysql> insert into EmployeeMaxAndSecondMaxSalary values(7,'James',68789); Query OK, 1 row affected (0.12 sec) mysql> insert into EmployeeMaxAndSecondMaxSalary values(8,'Robert',76543); Query OK, 1 row affected (0.13 sec)
使用 select 語句顯示錶中的所有記錄。查詢如下所示 -
mysql> select *from EmployeeMaxAndSecondMaxSalary;
輸出如下 -
+------------+--------------+----------------+ | EmployeeId | Employeename | EmployeeSalary | +------------+--------------+----------------+ | 1 | John | 34566 | | 2 | Bob | 56789 | | 3 | Carol | 44560 | | 4 | Sam | 76456 | | 5 | Mike | 65566 | | 6 | David | 89990 | | 7 | James | 68789 | | 8 | Robert | 76543 | +------------+--------------+----------------+ 8 rows in set (0.00 sec)
以下查詢可使用 limit offset 獲取最高和第二高的工資 -
mysql> select EmployeeId,Employeename,EmployeeSalary from EmployeeMaxAndSecondMaxSalary order by -> EmployeeSalary desc limit 2 offset 0;
輸出顯示 2 名最高工資員工的資訊 -
+------------+--------------+----------------+ | EmployeeId | Employeename | EmployeeSalary | +------------+--------------+----------------+ | 6 | David | 89990 | | 8 | Robert | 76543 | +------------+--------------+----------------+ 2 rows in set (0.00 sec)
更新於: 30-6-2020
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