对不起,我必须在这里更具体。以下是SQL我的代码。复制并粘贴SQL。基本上,我创建了13个链接在一起的表。
IF EXISTS (SELECT*FROM INFORMATION_SCHEMA.TABLES WHERE TABLE_NAME='EventType')
BEGIN
DROP TABLE EventType
END
GO
IF EXISTS (SELECT*FROM INFORMATION_SCHEMA.TABLES WHERE TABLE_NAME='EventLocation')
BEGIN
DROP TABLE EventLocation
END
GO
IF EXISTS (SELECT*FROM INFORMATION_SCHEMA.TABLES WHERE TABLE_NAME='StudentEvent')
BEGIN
DROP TABLE StudentEvent
END
GO
IF EXISTS (SELECT*FROM INFORMATION_SCHEMA.TABLES WHERE TABLE_NAME='Event')
BEGIN
DROP TABLE Event
END
GO
IF EXISTS (SELECT*FROM INFORMATION_SCHEMA.TABLES WHERE TABLE_NAME='CurrentAddress')
BEGIN
DROP TABLE CurrentAddress
END
GO
IF EXISTS (SELECT*FROM INFORMATION_SCHEMA.TABLES WHERE TABLE_NAME='PreviousAddress')
BEGIN
DROP TABLE PreviousAddress
END
GO
IF EXISTS (SELECT*FROM INFORMATION_SCHEMA.TABLES WHERE TABLE_NAME='ContactType')
BEGIN
DROP TABLE ContactType
END
GO
IF EXISTS (SELECT*FROM INFORMATION_SCHEMA.TABLES WHERE TABLE_NAME='Contact')
BEGIN
DROP TABLE Contact
END
GO
IF EXISTS (SELECT*FROM INFORMATION_SCHEMA.TABLES WHERE TABLE_NAME='StudentMajor')
BEGIN
DROP TABLE StudentMajor
END
GO
IF EXISTS (SELECT*FROM INFORMATION_SCHEMA.TABLES WHERE TABLE_NAME='Major')
BEGIN
DROP TABLE Major
END
GO
IF EXISTS (SELECT*FROM INFORMATION_SCHEMA.TABLES WHERE TABLE_NAME='Citizenship')
BEGIN
DROP TABLE Citizenship
END
GO
IF EXISTS (SELECT*FROM INFORMATION_SCHEMA.TABLES WHERE TABLE_NAME='Country')
BEGIN
DROP TABLE Country
END
IF EXISTS (SELECT*FROM INFORMATION_SCHEMA.TABLES WHERE TABLE_NAME='Student')
BEGIN
DROP TABLE Student
END
GO
CREATE TABLE Student
(
StudentID int identity PRIMARY KEY,
FirstName varchar (50),
LastName varchar (30)
)
GO
CREATE TABLE Country
(
CountryID int identity PRIMARY KEY,
CountryOfBirth varchar (10),
StudentID int FOREIGN KEY REFERENCES Student(StudentID)
)
GO
CREATE TABLE Citizenship
(
CitizenshipID int identity PRIMARY KEY,
CountryOfCitizenship1 varchar (10),
CountryOfCitizenship2 varchar (10),
StudentID int FOREIGN KEY REFERENCES Student(StudentID),
CountryID int FOREIGN KEY REFERENCES Country(CountryID)
)
GO
CREATE TABLE Major
(
Majorid int identity PRIMARY KEY,
MajorName varchar(30),
GraduatedMajor varchar (30)
)
CREATE TABLE StudentMajor
(
StudentMajorid int identity,
StudentID int FOREIGN KEY REFERENCES Student(StudentID),
MajorID int FOREIGN KEY REFERENCES Major(MajorID)
)
GO
ALTER TABLE StudentMajor
ADD constraint uk_sm UNIQUE (StudentID,MajorID)
CREATE TABLE Contact
(
ContactId int identity PRIMARY KEY,
StudentID int FOREIGN KEY REFERENCES Student(StudentID),
ContactInfo varchar (8),
ContactDate datetime
)
GO
CREATE TABLE ContactType
(
ContactTypeId int identity PRIMARY KEY,
ContactID int FOREIGN KEY REFERENCES Contact(ContactID)
)
GO
CREATE TABLE PreviousAddress
(
PreviousAddressId int identity PRIMARY KEY,
Address1 varchar (50),
Address2 varchar (50),
City varchar (20),
State varchar (20),
Pincode char (10),
StudentID int FOREIGN KEY REFERENCES Student(StudentID)
)
GO
CREATE TABLE CurrentAddress
(
CurrentAddressId int identity PRIMARY KEY,
Address1 varchar (50),
Address2 varchar (50),
City varchar (20),
State varchar (20),
Pincode char (10),
StudentID int FOREIGN KEY REFERENCES Student(StudentID)
)
GO
CREATE TABLE EventType
(
EventTypeID int identity PRIMARY KEY
)
CREATE TABLE Event
(
EventId int identity PRIMARY KEY,
EventDate datetime,
EventTitle varchar (50),
EventTime datetime,
EventTypeID int
)
GO
ALTER TABLE Event
ADD constraint fk_Event
FOREIGN KEY (EventTypeID) REFERENCES EventType(EventTypeID)
CREATE TABLE StudentEvent
(
StudentEventId int identity PRIMARY KEY,
StudentID int FOREIGN KEY REFERENCES Student(StudentID),
EventID int FOREIGN KEY REFERENCES Event(EventID),
Comment varchar(2000)
)
GO
CREATE TABLE EventLocation
(
EventLocationId int identity PRIMARY KEY,
EventCountry varchar (50),
EventState varchar (50),
EventAddress1 varchar (100),
EventAddress2 varchar (100),
EventCity varchar (50),
EventPincode char (10),
EventID int FOREIGN KEY REFERENCES Event(EventID)
)
GO
现在上面代码的问题在于它会第一次完美执行,但是当我第二次执行时它会抛出我的错误。
无法删除对象' EventType'因为它是由FOREIGN KEY约束引用的。
Msg 2714,Level 16,State 6,Line 132
已有一个名为' EventType'在数据库中。Msg 4902,Level 16,State 1,Line 143
找不到对象"事件"因为它不存在或您没有权限。Msg 1767,Level 16,State 0,Line 153
外键' FK__EventLoca__Event__6265874F'引用无效表'事件'。 Msg 1750,Level 16,State 0,Line 153无法创建约束或索引。查看以前的错误。
是否有更好的方法来编写外键或我做错了什么。
提前感谢您的帮助!
答案 0 :(得分:2)
您应首先创建表格:
CREATE TABLE Event
(
EventId int identity PRIMARY KEY,
EventDate datetime,
EventTitle varchar (50),
EventTime datetime,
EventTypeID int
)
GO
CREATE TABLE EventType
(
EventTypeID int identity PRIMARY KEY
);
ALTER TABLE Event
ADD constraint fk_Event
FOREIGN KEY (EventTypeID) REFERENCES EventType(EventTypeID);
或者您可以将表格创建为:
CREATE TABLE EventType
(
EventTypeID int identity PRIMARY KEY
);
CREATE TABLE Event
(
EventId int identity PRIMARY KEY,
EventDate datetime,
EventTitle varchar (50),
EventTime datetime,
EventTypeID int,
constraint fk_Event FOREIGN KEY (EventTypeID) REFERENCES EventType(EventTypeID)
);
更新
无法删除对象' EventType'因为它是由FOREIGN KEY约束引用的。 Msg 2714,Level 16,State 6,Line 132已经有一个名为' EventType'在数据库中。消息4902,级别16,状态1,行143无法找到对象"事件"因为它不存在或您没有权限。消息1767,等级16,状态0,行153外键' FK__EventLoca__Event__6265874F'引用无效表'事件'。消息1750,级别16,状态0,行153无法创建约束或索引。查看以前的错误。
这个错误消息很清楚,你不能删除另一个表中引用的表,所以你必须首先删除Event
表,然后你可以删除EventsType
表。 / p>
答案 1 :(得分:0)
尝试创建表EventType
,然后将其用作表Event
中的参考。