mysql学习打卡day22

今日成果：

select * from employees
where salary > (select avg(salary) from employees);
-- 查询超过平均工资的员工

select * from clients
where client_id not in (select  distinct client_id from invoices);
-- 查询没有发票的用户 

感谢各位读者查阅，欢迎各位点赞✍评论⭐收藏+关注！