2(a)
(i)
Create table staffs(Staff_Id integer not null primary key,
Name varchar(255),
Staff_Type varchar(255),
Session_Id integer not null);
select * from staffs;
(ii)
Create table Customers(Customer_Name Varchar(255) primary key);
select * from customers
(iii)
Create table Freelancers (Freelancer_Name varchar(255) primary key,
Freelancer_Type Varchar(255));
select * from freelancers;
(iv)
Create table Studio(Record_studio Integer not null primary key);
select * from studio;
(v)
drop table sessions;
Create table Sessions(Session_No integer not null primary key,
Session_Type varchar(255),
Session_Title varchar(255),
Session_Date varchar(255),
Customer_Name varchar(255),
Staff_Id integer,
Freelancer_Name varchar(255),
Record_Studio integer);
ALTER TABLE Sessions
ADD FOREIGN KEY
(Customer_Name) REFERENCES Customers(Customer_Name);
ALTER TABLE Sessions
ADD FOREIGN KEY
(Staff_Id) REFERENCES Staffs(Staff_Id);
ALTER TABLE Sessions
ADD FOREIGN KEY
(Freelancer_name) REFERENCES Freelancers(Freelancer_Name);
ALTER TABLE Sessions
ADD FOREIGN KEY
(Record_Studio)REFERENCES Studio(Record_Studio);
select * from Sessions;
下面的语句给了我错误"不能添加外键约束"
链接到错误mysql错误代码http://dev.mysql.com/doc/refman/5.6/en/error-messages-server.html#error_er_cannot_add_foreign
ALTER TABLE Staffs
ADD FOREIGN KEY (Session_Id) REFERENCES Sessions(Sessions_No);
好的,我认为这是一个打字错误。
ALTER TABLE工作人员添加外键(Session_Id)REFERENCES会话(Session_No)
回答
ALTER TABLE工作人员添加外键(Session_Id)REFERENCES会话(Session_No)