07 2021 档案

记录一句sql语句
摘要：查询每个部门的员工个数： select d.department_id, ( select count(*) from employees e where e.department_id = d.department_id ) 个数 from departments d; 一个直接的思路是将两张表外 阅读全文
posted @ 2021-07-22 19:58 imissinstagram 阅读(65) 评论(0) 推荐(0)