分析员工在不同项目中的绩效表现以及所属部门的平均绩效情况

DROP TABLE IF EXISTS employee_projects;
DROP TABLE IF EXISTS department_info;
-- 创建表
CREATE TABLE employee_projects (
    employee_id INT PRIMARY KEY,
    project_id INT,
    performance_score INT
);

CREATE TABLE department_info (
    employee_id INT PRIMARY KEY,
    department_id INT ,
    department_name VARCHAR(50)
);

-- 插入数据
INSERT INTO employee_projects (employee_id, project_id, performance_score)
VALUES (1, 1, 85),
       (2, 2, 90),
       (3, 1, 75),
       (4, 2, 75),
       (5, 2, 90);

INSERT INTO department_info (employee_id, department_id,department_name)
VALUES (1, 1, '研发部'),
       (2, 2, '市场部'),
       (3, 1, '研发部'),
       (4, 2, '市场部'),
       (5, 2, '市场部');

select * from employee_projects;
select * from department_info;

employee_id|department_name|performance_score
1|研发部|85
2|市场部|90
5|市场部|90