1 Navicat无法连接数据库的解决办法
打开【win+r】输入CMD进入命令行界面，然后输入
alter user 'root'@'localhost' identified by '密码' password expire never;
alter user 'root'@'localhost' identified with mysql_native_password by '密码';
flush privileges;
记得将密码替换为mysql 的密码。
6.关于mysql数据库视图
视图：select查询结果的一个虚拟表。
6-1 创建视图
代码块
EATE VIEW stu_salary_view
as
SELECT * from student WHERE salary>5000 with CHECK option;
with CHECK option 表示修改视图时候，salary必须大于5000，否则无法保存。
6-2使用视图
代码块
SELECT * from stu_salary_view WHERE stu_age=24;
6-3替换原来的视图
覆盖原来的视图
代码块
CREATE OR REPLACE VIEW stu_salary_view
as
(SELECT * from student )
6-4删除视图
DROP VIEW stu_salary_view;
7创建一个学生的数据库
代码块
-- 创建学院表
CREATE TABLE college(
id int(11) NOT NULL AUTO_INCREMENT,
name varchar(30) NOT NULL,
PRIMARY KEY (id)
) ;
-- 创建表班级
CREATE TABLE class (
id int(11) NOT NULL AUTO_INCREMENT,
name varchar(30) NOT NULL,
belong_college int(11) DEFAULT NULL,
PRIMARY KEY (id),
CONSTRAINT class_college_fk FOREIGN KEY (belong_college) REFERENCES college(id)
) ;
-- 创建表班级
CREATE TABLE student(
id int PRIMARY KEY ,
stu_name varchar(20) not null,
age int not null,
gender varchar(6) not null,
number int not null,
birth datetime check(birth > '1990-1-1')
stu_class int,
CONSTRAINT student_class_fk FOREIGN KEY (stu_class) REFERENCES class(id)
);
-- 创建老师表
create table teacher
(
id int auto_increment primary key,
tea_name varchar(20) not null,
tea_class int,
CONSTRAINT teacher_class_fk FOREIGN KEY (tea_class) REFERENCES class(id)
);
-- 创建课程表
create table course
(
id int auto_increment primary key,
cou_name varchar(50) not null,
cou_time tinyint check(cou_time>0 and cou_time<100),
cou_teacher int not null,
CONSTRAINT course_teacher_fk FOREIGN KEY (cou_teacher) REFERENCES teacher(id)
);
-- 创建成绩表
create table score
(
score_course int,
score_number int,
score int,
CONSTRAINT score_course_fk FOREIGN KEY(score_course) REFERENCES course(id),
CONSTRAINT score_student_fk FOREIGN KEY(score_number) REFERENCES student(id)
);
