create table `student`( `id` int(11) not null auto_increment, `name` char(50) not null comment '学生姓名', `sid` int(11) not null comment '学号', primary key(`id`), unique key `sid`(`sid`) )engine = innodb; create table `course`( `id` int(11) not null auto_increment, `name` char(50) not null comment '课程名称', `score` int(11) not null comment '成绩', `sid` int(11) not null comment '学号', primary key(`id`) )engine = innodb;