The Employee
table holds all employees. Every employee has an Id, a salary, and there is
also a column for the department Id.
+----+-------+--------+--------------+ | Id | Name | Salary | DepartmentId | +----+-------+--------+--------------+ | 1 | Joe | 70000 | 1 | | 2 | Henry | 80000 | 2 | | 3 | Sam | 60000 | 2 | | 4 | Max | 90000 | 1 | +----+-------+--------+--------------+
The Department
table holds all departments of the company.
+----+----------+ | Id | Name | +----+----------+ | 1 | IT | | 2 | Sales | +----+----------+
Write a SQL query to find employees who have the highest salary in each of the departments. For the above tables, Max has the highest salary in the IT department and Henry has the highest salary in the Sales department.
+------------+----------+--------+ | Department | Employee | Salary | +------------+----------+--------+ | IT | Max | 90000 | | Sales | Henry | 80000 | +------------+----------+--------+
创建表:
create table Employee
(
Id int NOT NULL AUTO_INCREMENT,
Name char(10) null,
Salary int null,
Departmentid int null,
primary key (Id)
);
INSERT INTO Employee(Id ,Name,Salary,Departmentid) values(1,"Joe",7000,1);
INSERT INTO Employee(Id ,Name,Salary,Departmentid) values(2,"Henry",8000,2);
INSERT INTO Employee(Id ,Name,Salary,Departmentid) values(3,"Sam",6000,2);
INSERT INTO Employee(Id ,Name,Salary,Departmentid) values(4,"Max",9000,1);
create table Department
(
Id INT NOT NULL auto_increment,
Name char(10) NULL,
primary key (Id)
);
insert into Department(Id, Name) values(1,"IT");
insert into Department(Id, Name) values(2,"Sales");
答案:
select D.name as Department1, E.name as Employee, E.Salary
from
Employee E,
Department D,
(select DepartmentId ,max(Salary) as max from Employee group by DepartmentId) T
where E.DepartmentId = T.DepartmentId
and E.Salary = T.max
and E.DepartmentId = D.id;