创建触发器，填入信息时自动填入日期

Question

编辑错误，文件不显示，尝试几次打完后全是错
是真的不会

（凑字数123456897）

Answer 1

1、create database students;
2、use students;
create table student (
student_id int PRIMARY KEY,
mingzi VARCHAR(5),
xingbie VARCHAR(2),
class_id int,
sheng datetime,
jiandangriqi datetime
);
create table class (
class_id int PRIMARY KEY,
class_title VARCHAR(3)
);
3、CREATE TRIGGER w_student  #触发器的名称，如有要求按要求命名，如没有自己随便命名
    AFTER INSERT             #当执行插入语句之后激活触发器
    ON students.student      #作用于那个表
    FOR EACH ROW             #触发器作用在每条记录上
    # 触发器需要执行的操作
    BEGIN
        #当插入一条学生记录就向student表插入当前日期为建档日期
        INSERT INTO students.student(jiandangriqi) VALUES (NOW());
    END;
4、 insert into student (student_id,mingzi,xingbie,class_id,sheng) values (1,'陈一','男',1,2002-01-05 00:00:00);
5、create view student_v as select student_id as 学号,mingzi as 名字,class_title as 班级名称,DATEDIFF(sheng,NOW()) as 年龄
from student s 
left join class c 
on s.class_id = c.class_id;
6、update student set class_id = 1 where mingzi = '张三';
7、select sum(DATEDIFF(sheng,NOW())) / count(*) from student where class_id = 2;