MySql学习笔记

MySql学习视频地址：

https://www.bilibili.com/video/BV1fx411X7BD?p=55&spm_id_from=pageDriver

 

P55：外键约束

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drop table if exists t_student; drop table if exists t_class;     create table t_class(     cno int primary key,     cname varchar(255) ); create table t_student (     sno int primary key,     sname varchar(255),     classno int,     foreign key(classno) references t_class(cno) ); insert into t_class values(101,"xxxxxxxxxxx"); insert into t_class values(102,"yyyyyyyyy");   insert into t_student values(1,"zs01",101); insert into t_student values(2,"zs02",101); insert into t_student values(3,"zs03",102); insert into t_student values(4,"zs04",102); insert into t_student values(5,"zs05",102);   select * from t_class; select * from t_student;