SELECT employee_id,department_name,performance_score
 FROM(   
    SELECT a.*,b.department_name,avg(a.performance_score) OVER (PARTITION BY project_id) AS avg
    FROM employee_projects AS a 
    JOIN department_info AS b ON a.employee_id = b.employee_id
 ) AS avg_tb
 WHERE performance_score > avg
 ORDER BY employee_id ASC

此题ez，先进行表连接然年后计算出每个项目的平均分,然后筛选出得分大于平均分的再用ID排序就好了