MySQL---3/29

Intergrity Constrait (完整性约束)

 Set table key‘s primary key

  mysql>create table student(

          >id int primary key,

          >name varchar(40),

          >sex boolean,

          >);

  Multiple-field primary key---consists of more than one property

    mysql>create table student2(

            >id int,

            >course_id int,

            >score float,

            >primary key(id,course_id)

            >);