向现有表添加外键 [英] Adding a foreign key to existing table
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问题描述
我一直试图将这些键添加到我的表中,但是出现错误
I have been trying to add these keys to my table but I get an error
ORA-01735:无效的ALTER TABLE选项
ORA-01735: invalid ALTER TABLE option
我的代码:
ALTER TABLE Room
ADD FOREIGN KEY (RoomType_ID) REFERENCES RoomType(RoomType_ID),
ADD FOREIGN KEY (Reservation_ID) REFERENCES Reservation(Reservation_ID),
ADD FOREIGN KEY (Gust_ID) REFERENCES Gust(Gust_ID);
表格
CREATE TABLE Gust ( Gust_ID INT NOT NULL PRIMARY KEY, First_Name VARCHAR(50), Last_Name VARCHAR(50), Email VARCHAR(20), phone_number INT(10), Address VARCHAR(30) )
CREATE TABLE Reservation ( Reservation_ID INT NOT NULL PRIMARY KEY, Start_Date Date, End_Date Date )
CREATE TABLE Room ( Room_ID INT NOT NULL PRIMARY KEY, Price INT )
CREATE TABLE RoomType ( RoomType_ID INT NOT NULL PRIMARY KEY, Class VARCHAR(10), ExtraPrice INT )
多个 FOREIGN KEYS
的
推荐答案
ALTER
语句不起作用.
每个 CONSTRAINT
应该单独添加:
CREATE TABLE Gust ( Gust_ID INT PRIMARY KEY, First_Name VARCHAR(50), Last_Name VARCHAR(50), Email VARCHAR(20), phone_number INT, Address VARCHAR(30) );
CREATE TABLE Reservation ( Reservation_ID INT PRIMARY KEY, Start_Date Date, End_Date Date );
CREATE TABLE RoomType ( RoomType_ID INT NOT NULL PRIMARY KEY, Class VARCHAR(10), ExtraPrice INT );
CREATE TABLE Room(Room_ID int PRIMARY KEY, Price INT, Reservation_ID int,Gust_ID int );
ALTER TABLE Room ADD FOREIGN KEY (Room_ID) REFERENCES RoomType(RoomType_ID);
ALTER TABLE Room ADD FOREIGN KEY (Reservation_ID) REFERENCES Reservation(Reservation_ID);
-- the table Room is assumed to have a column Reservation_ID
ALTER TABLE Room ADD FOREIGN KEY (Gust_ID) REFERENCES Gust(Gust_ID);
-- the table Room is assumed to have a column Gust_ID
如果不需要系统生成的约束名称,则使用这些;
If System-generated constraint name not to be wanted, then using these ;
ALTER TABLE Room ADD CONSTRAINT fk_RoomType_ID FOREIGN KEY (Room_ID)
REFERENCES RoomType(RoomType_ID);
ALTER TABLE Room ADD CONSTRAINT fk_Reservation_ID FOREIGN KEY (Reservation_ID)
REFERENCES Reservation(Reservation_ID);
ALTER TABLE Room ADD CONSTRAINT fk_Gust_ID FOREIGN KEY (Gust_ID)
REFERENCES Gust(Gust_ID);
可能是首选.
P.S.:
- 请勿在
PRIMARY KEY
和PRIMARY KEY
中使用NOT NULL
包括NOT NULL
. - 不能为
INT
列定义长度.
- Do Not Use
NOT NULL
withPRIMARY KEY
,PRIMARY KEY
already includesNOT NULL
. - The length can not be defined for an
INT
column.
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