# 分组查询
/*
语法：
SELECT 分组函数，列（要求出现在group by的后面）、
FROM 表名
WHERE 筛选条件
GROUP BY 分组的列表
ORDER BY 子句
*/
SELECT AVG(salary), department_id
FROM employees
GROUP BY department_id;
SELECT max(salary), job_id
FROM employees
GROUP BY job_id
ORDER BY max(salary);
SELECT COUNT(*),location_id
FROM departments
GROUP BY location_id;
SELECT AVG(salary),email,department_id
FROM employees
WHERE email LIKE '%a%'
GROUP BY department_id;
SELECT MAX(salary), manager_id
FROM employees
WHERE commission_pct is NOT NULL
GROUP BY manager_id;
-- 62
