Question

2（a）中

（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;

下面的语句给出了错误＆＃34;无法添加外键约束＆＃34;

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);

??????????????????????????????????????????????? ？

Answer 1

好的，我认为这是一个拼写错误。

ALTER TABLE Staffs ADD FOREIGN KEY（Session_Id）REFERENCES Sessions（Sessions_No）

回答

ALTER TABLE Staffs ADD FOREIGN KEY（Session_Id）REFERENCES Sessions（Session_No）

得到错误＆＃34;无法添加外键约束＆＃34;在我最后的mysql版本中

1 个答案: