#案例：查询员工的工资级别
SELECT salary,grade_level FROM employees e JOIN job_grades g ON e.`salary` BETWEEN g.`lowest_sal` AND g.`lowest_sal`;
#案例：查询每个工资级别的个数，并且按级别降序
SELECT COUNT(*),grade_level FROM job_grades j JOIN employees e ON e.`salary` BETWEEN j.`lowest_sal`AND j.`highest_sal` GROUP BY grade_level DESC;
内容扩展：
语法
select 查询列表
from 表1 别名 [连接类型]
jion 表2 别名
on 连接条件
[where 筛选条件]
[group by 分组]
[having 筛选条件]
[order by 排序列表]
案例1:查询员工名,部门名
SELECT last_name,department_name FROM employees e INNER JOIN departments d ON e.department_id=d.department_id;
案例2:查询名字中包含e的员工名和工种名(添加筛选)
SELECT last_name,job_title FROM employees e INNER JOIN jobs j ON e.job_id=j.job_id WHERE e.last_name LIKE ‘%e%';
以上就是本次介绍的全部知识点内容。
