根据如下需求，定义视图

1、为了保证数据库表的安全性，开发人员在操作tb_user表时，只能看到的用户的基本手段，屏蔽手机号和邮箱两个字段

create view tb_user_view as select id,name,profession,age,gender,status,createtime from tb_user;
select * from tb_user_view;#验证

2、查询每个学生所选修的课程(三张表联查)，这个功能在很多的业务中都有使用到，为了简化操作，定义一个视图

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select s.name as student_name,s.no as student_no,c.name as course_name from student as s,student_course as sc,course c where
s.id = sc.studentid and sc.courseid = c.id;#多表联查
create view tb_stu_course_view as select s.name as student_name,s.no as student_no,c.name as course_name from
student as s,student_course as sc,course c where s.id = sc.studentid and sc.courseid = c.id;#视图
#优点:后续不需要每次都写这条多表联查的SQL，我们只需要查看视图就可以了，如下
select * from tb_stu_course_view;#验证

视图的优点: 视图相当于封装查询语句，简化了操作，跟用函数一样