数据库设计工具的使用（实用）

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/* DBMS name: MySQL 5.0 */
/* Created on: 2017/5/27 0:57:18 */
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drop table if exists Teacher;

drop table if exists course;

drop table if exists teach;

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/* Table: Teacher */
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create table Teacher ( tid int not null, teacherName varchar(20) not null, sex char(1) not null default 'm', birthday date, major varchar(30), primary key (tid) );

alter table Teacher comment '教师实体对象，存放教师信息';

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/* Table: course */
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create table course ( cid int not null, cname varchar(20) not null, chour int, credit numeric(2,0), primary key (cid) );

alter table course comment '课程信息';

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/* Table: teach */
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create table teach ( tid int not null, cid int not null, starttime datetime, primary key (tid, cid) );

alter table teach add constraint FK_teach foreign key (tid) references Teacher (tid) on delete restrict on update restrict;

alter table teach add constraint FK_teach2 foreign key (cid) references course (cid) on delete restrict on update restrict;