李玉婷MYSQL进阶12-视图

视图

含义：虚拟表，和普通表一样使用。mysql15.1版本出现的新特性，是通过表动态生成的数据。

 

一、创建视图

语法：

create view 视图名

as

查询语句；

案例1:查询姓名中包含a字符的员工名、部门名和工种信息

CREATE VIEW myv1
AS

SELECT last_name,department_name,job_title
FROM employees e
JOIN departments d ON e.department_id=d.department_id
JOIN jobs j ON e.job_id=e.job_id;

SELECT * FROM myv1 where last_name LIKE '%a%';

案例2:查询各个部门的平均工资级别

CREATE VIEW myv2
AS
SELECT AVG(salary) ag,department_id
FROM employees
GROUP BY department_id;

SELECT myv2.ag,g.grade_level
FROM myv2
JOIN job_grades g
ON myv2.ag BETWE