mysql中的主外键实例 博客分类： sql MySQL

mysql中如果要设置主外键关联的话，其数据库的类型必须市INNODB类型的；

自己练习时给个示例：

CREATE TABLE Department( 
    DepartmentId int(11)  NOT  NULL  AUTO_INCREMENT ,
    部門 varchar(30),
      CONSTRAINT Department_pk PRIMARY KEY (DepartmentId)
) TYPE=INNODB CHARACTER SET utf8 COLLATE utf8_unicode_ci;

insert into Department(部門) values('销售部')
insert into Department(部門) values('开发部')

CREATE  TABLE Employee(
    EmployeeId int(11)  NOT  NULL  AUTO_INCREMENT ,
    LastName varchar(30) ,
    --外键一定是要定义索引，且它一定是int或integer类型
    DepartmentID int(11),
    --这里只是定义主索引，constranit是约束的意思
    CONSTRAINT Employee_pk PRIMARY  KEY ( EmployeeId ),
    INDEX (DepartmentID)
) TYPE=INNODB CHARACTER SET utf8 COLLATE utf8_unicode_ci;
insert into Employee(`DepartmentID`,`LastName`) values(1,'keith')
insert into Employee(`DepartmentID`,`LastName`) values(2,'given')
insert into Employee(`DepartmentID`,`LastName`) values(1,'scach')
insert into Employee(`DepartmentID`,`LastName`) values(2,'tom')