Create A Foreign Key To Unique Constraint?
Jul 3, 2015
why it is not possible to create a Foreign key to a Unique constraint?
Table A has column 1 holding a Primay key and two columns (2 and 3) holding a Unique combination (and some more columns).He created an Unique constraint on column 2 and 3 together.
He wanted to use this Unique combination to point to table B (instead of the table 1's PK) so he tried to create a foreign key on a column in table B but an error popped up prompting;
The columns in table 'TABLE_A' do not match an existing primary key or UNIQUE constraint.
Ok - these two columns ar no PK but the hold an Unique constraint......
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Nov 3, 2000
I am attempting to create a unique constraint on an nvarchar field named theology (it is not the primary key field)
that allows nulls. The table contains multiple rows with the value of null for
field theology. The documentation says one can create a unique constraint on a
field with all unique value except for null. Here is the error message:
'testtable1' table
- Unable to create index 'IX_testtable1'.
ODBC error: [Microsoft][ODBC SQL Server Driver][SQL Server]CREATE UNIQUE INDEX
terminated because a duplicate key was found. Most significant primary key
is ''.
[Microsoft][ODBC SQL Server Driver][SQL Server]Could not create constraint. See
previous errors.
Any ideas? I am creating a unique constraint and not a unique index. Is there
some other database option to set to allow this?
.
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Feb 12, 2006
Hello.
Could anyone tell me why it is not possible to create a foreign key on two columns those references on 2 columns in another table? Those 2 columns have each a unique constraint.
I have:
CREATE TABLE T_PK (ID1 INT CONSTRAINT CHK_UNIQUE1 UNIQUE,ID2 INT CONSTRAINT CHK_UNIQUE2 UNIQUE)
CREATE TABLE T_FK (ID1 INT, ID2 INT)
And I want to do:
ALTER TABLE T_FK ADD CONSTRAINT CHK_FK FOREIGN KEY (ID1, ID2) REFERENCES T_PK (ID1,ID2)
I see no reason why this is not working because always
a row in the table T_FK referencing only one row in table T_PK.
Thank you.
Have a nice day.
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May 5, 2008
I am trying to create a Unique Constraint on a SQL Server 2005 table where the uniqueness is based on 2 columns.
Could anybody provided some help on how I could enforce this on an existing table (link, or example) I have been looking around without luck.
Thanks in advance
John.
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Apr 5, 2004
Hi all,
I am trying to add a unique index/constraint on a column that allows NULL values. The column does have NULL values and when I try to create a unique constraint, I get the following error.
CREATE UNIQUE INDEX terminated because a duplicate key was found for index ID 9. Most significant primary key is '<NULL>'.
Are'nt you allowed to create a UNIQUE constraint on a NULL column? Books Online says that you are allowed to create a unique constraint on NULL columns, then why am I getting this error.
Any help would be appreciated.
Thanks,
Amir
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Sep 22, 2004
A UNIQUE INDEX must inherently impose a unique constraint and a UNIQUE CONSTRAINT is most likely implemented via a UNIQUE INDEX. So what is the difference? When you create in Enterprise Manager you must select one or the other.
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Jul 20, 2005
HelloWhat should I use for better perfomance sinceunique constraint always use index ?ThanksKamil
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Jun 24, 2006
What's the difference in the effect of the followings:
CREATE UNIQUE NONCLUSTERED INDEX
and
ALTER TABLE dbo.titles ADD CONSTRAINT
titleind UNIQUE NONCLUSTERED
I found there're two settings in Indexs/Keys dialog box of the management studio, Is Unique, and Type. The DDL statements above are generated by setting Is Unique to yes plus Type to Index, and just Type to Unique Key, respectively. What's the difference between them?
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May 13, 2008
We are using SQL CE 3.5 on tablet PCs, that synchs with our host SQL 2005 Server using Microsoft Synchronization Services. On the tablets, when inserting a record, we get the following error:
A duplicate value cannot be inserted into a unique index. [ Table name = refRegTitle,Constraint name = PK_refRegTitle
But the only PK on this table is RegTitleID.
The table structure is:
[RegTitleID] [int] IDENTITY(1,1) NOT NULL,
[RegTitleNumber] [int] NOT NULL,
[RegTitleDescription] [varchar](200) NOT NULL,
[FacilityTypeID] [int] NOT NULL,
[Active] [bit] NOT NULL,
The problem occurs when a Title Number is inserted and a record with that number already exists. There is no unique constraint on Title Number.
Has anyone else experienced this?
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Mar 7, 2001
Hi everyone,
I need urgent help to resolve this issue...
As far as the performance goes which one is better..
Unique Index(col1, col2) OR Unique constraint(col1, col2) ?
Unique constraint automatically adds a unique index
and unique index takes care of uniqueness then whats the use of unique constraint ?
Which one do one use ?
thanks
sonali
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Jan 20, 2006
BOL says a unique constraint is preferred over a unique index. It also states that a unique constraint creates a unique index. What then is the difference between the two, and why is a constraint preferred over the index?
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Aug 11, 1999
student --- enrollment is 1- to - many . ssn is pk in student. ssn and courseid is pk in enrollment. later I added the foreign key constraint FK_SSN in enrollment table reference student table. it is ok.
enrollment --- lessonhistory is 1-to -many, ssn, courseid and lessonid is pk in lessonhistory . I tried to set FK_SSN foreign key constraint in lessonhistory table reference enrollment table, it always show error message " no primary key in referewnce talbe enrollment "
I don't know how to fix it. could you help me out, thanks!!
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Nov 20, 2011
I have a created a database with nearly 20 tables in it, so I cannot post all of my statements. I am having an issue though with two tables' referential integrity when it comes to foreign key constraints. I want to constrain them to cascade updates from the primary key tables, but I keep getting the error msg 1785
Introducing FOREIGN KEY constraint 'FK__PURCHASE___ITEM___64F971E5' on table 'PURCHASE_ORDER_LINE' may cause cycles or multiple cascade paths. Specify ON DELETE NO ACTION or ON UPDATE NO ACTION, or modify other FOREIGN KEY constraints.
Here is the table with the primary key:
create table MERCHANDISE (
ITEM_ID varchar (8) NOT NULL PRIMARY KEY,
DESCRIPTION CHAR (60),
STANDARD_PRICE MONEY,
[code]...
I have tried making an update trigger but it does not work.
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Apr 25, 2006
i have a publication that is composed of
many articles. The publication is composed of many
realated tables. I'm doing a snapshot replication
Is there a way to specify the order by which table
must synchonize.
lets say. article 1 synchonizes first, then article 3, then article 2
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Jan 3, 2002
Hi
I am attempting to write a DTS package that copies the data across from one instance of a db on a test server to a second instance on to the live server. It has to replace all the exisiting date so I can't append. Unfortunately, the package keeps giving me errors all of the type "unable to truncate tbl due to foreign key constraints". Is there a way round this?
Thanks
Steve
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Jan 11, 2007
sql 2000, northwind databse
code in sql analyzer:
Code:
ALTER TABLE categories NOCHECK CONSTRAINT ALL
TRUNCATE TABLE categories
ALTER TABLE categories CHECK CONSTRAINT ALL
but still i am getting the error:
Quote: Server: Msg 4712, Level 16, State 1, Line 2
Cannot truncate table 'categories' because it is being referenced by a FOREIGN KEY constraint.
what i need to do is write a query that just cleans all the tables of all data.
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Feb 10, 2004
"Introducing FOREIGN KEY constraint 'FK__APPLICANTMA__SEX__414EAC47' on table 'APPLICANTMASTER' may cause cycles or multiple cascade paths. Specify ON DELETE NO ACTION or ON UPDATE NO ACTION, or modify other FOREIGN KEY constraints."
ive a foreign key reference on the table APPLICANT MASTER
of the form
FOREIGN KEY (SEXCODE) REFERENCES
APPLICANTSEX(SEXCODE)
ON DELETE NO ACTION
ON UPDATE CASCADE,
can any one help me WHAT THE MESSAGE MEANS ?
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Apr 9, 2008
Hi all, I'm new here so I hope this is the right place to post!!
I'm having a really big problem trying to make a table. I'm not new to the coding, but I'm no expert either.... as far as I can see I haven't done anything wrong...
I have many tables, but the first two are JobDetails and Promotions... in JobDetails, there is a primary key Job which needs to link to Promotions as a foreign key.... here is my code and errors, I'd really appreciate some help...
create table JOBDETAIL
(Job varchar2(15) primary key,
Dept varchar2(10) not null,
Salary number(7) not null);
create table PROMOTION
(PCID number(6) primary key,
PDate date,
Constraint fkey_p1 foreign key (Job) references JOBDETAIL(Job));
ERROR at line 4:
ORA-00904: "Job": invalid identifier
... any help would be appreciated, this is quite important... thank you!!!
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Dec 13, 2007
Here is my sqlce:
Code Block
alter table tblV
add constraint
foreign key (T_ID)
references tblT(T_ID)
on delete set null on update cascade
Error is:
Major Error 0x80040E14, Minor Error 25501
There was an error parsing the query. [ Token line number = 3,Token line offset = 1,Token in error = foreign ]
I'm new with SQL Mobile, so sorry for the novice question.
Thanks
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Jan 21, 2007
Hi,
I am fairly new to SQL server Express and I have quite a simple database set up and I am trying to test it out with data. I have €śPain Reading€? and €śWorsen Factors€? tables with a 1: M relationship. The primary key in the Pain reading table is ReadingID which is being set using getdate() for the default value. I am getting the following error when attempting to add a new row to the €śWorsen Factors€? table:
No row was updated
The data in row 1 was not committed.
Error source:.Net SqlClient Data Provider
Error Message: The insert statement conflicted with the FOREIGN KEY constraint "FK_WorsenFactor_PainReading1". The confilct occurred in database "paindata", table "dbo.PainReading", column 'ReadingID'.
The statement has been terminated.
Any help or suggestions would be very helpful.
Thanks
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Aug 1, 2007
I have two tables; each has multi-column primary keys. I need to create a foreign key relationship between the two tables.
Sales:
DKey, int, PK
OKey,int, PK
RKey,int, PK
...
Rep:
Bkey, int, PK, identity
Rkey, int, PK
...
When I try to like Rkey from both tables as a foreign key relationship, I get an error that the columns in one table "do not match an existing primary key or UNIQUE constraint. (I've tried it both ways and get the same error.)
How can I link these two tables?
Thanks.
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Dec 3, 2007
Hi,
i have two tables, one is department-Table(Master table) and other is employee-table(Child table).
DNO is a data field which is common in both the table. "DNO" is primary key in department-table and "DNO" is foreign key in child table.
I am trying to insert rows in the table i found the following error:
The INSERT statement conflicted with the FOREIGN KEY constraint "FK_Employee_Department". The conflict occurred in database "Project", table "dbo.Department", column 'Dno'.
What's the solution to replace this error
Thanks.
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Oct 11, 2006
Hi there
Yesterday I made alot of updates to to various tables within a databse, to update some records I had to drop the foreign key constraint, but when I try to add the constraint back I get an error message (in red)
ALTER TABLE [dbo].[ITEMS] ADD
CONSTRAINT [FK_ITEMS__ITEM_CATEGORIES] FOREIGN KEY
(
[ITC_ID]
) REFERENCES [dbo].[ITEM_CATEGORIES] (
[ITC_ID]
) ON UPDATE CASCADE NOT FOR REPLICATION ,
CONSTRAINT [FK_ITEMS__ITEM_TYPES] FOREIGN KEY
(
[ITY_ID]
) REFERENCES [dbo].[ITEM_TYPES] (
[ITY_ID]
) ON UPDATE CASCADE NOT FOR REPLICATION
GO
Server: Msg 1785, Level 16, State 1, Line 1
Introducing FOREIGN KEY constraint 'FK_ITEMS__ITEM_CATEGORIES' on table 'ITEMS' may cause cycles or multiple cascade paths. Specify ON DELETE NO ACTION or ON UPDATE NO ACTION, or modify other FOREIGN KEY constraints.
Server: Msg 1750, Level 16, State 1, Line 1
Could not create constraint. See previous errors
any suggestions? I tried modifying the statement to ON UPDATE NO ACTION, but I get exactly the same error message.
Any help would be much appreciated...thanks in advance
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Aug 9, 2007
A website that I'm working on has users sign in and keeps a log of the pages they go to. The log table has a foreign key in it that links to the username is the users table. I need to update the username for one of the users but the foreign key is preventing me from doing so. What is the benefit of having a foreign key like this? Can I delete it to update the username or is there a better way?
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Nov 2, 2007
Hi,
I don't know if this is possible, i believe not, so I'm here to ask the experts if is possible to have a foreign key constraint that references the key of one of two tables.
Like this:
I have 3 tables: TABLE X, TABLE A and TABLE B
Is it possible to the FK on TABLE X refernce the PK of TABLE A OR TABLE B?
If yes, how can I do this?
If not, I need to have a fourth table, so TABLE X references TABLE A and TABLE Y references TABLE B.
Thanks!
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Mar 6, 2008
I have two tables: table 1 and table 2. The primary key of table is composite key of two collumns and table 2 is the child of parent table 1. Is it possible to create / define a foreign key constraint using a composite primary key?
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Mar 1, 2001
I have to drop foreign key constraint from one table. How can I do that? Is it possible?
Also,
Is it possible to add a foreign key constraint on the table once it has a data?
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Mar 17, 2004
I am importing data from a flat, comma delimited text file. It appears to properly import all the records and then on the last record it give me the error
INSERT statement conflicted with COLUMN FOREIGN KEY constraint for 'EOR_ITE_REF_EOR'.
Then it goes on to tell me the database, table and column in which the problem occured which is the first column in the table. It looks like it doesn't like the end of the file for some reason (EOR, end of record?) so I tried deleting the last record from the file and it still does it. I do have a file that I have imported that worked so I tried copying the last record of that file and pasting it into the last record of the file I wanted but that did not work either. The ends of file that works and the file that doesn't work look the same and I can find nothing on 'EOR_ITE_REF_EOR'. Any help would be appreciated.
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Mar 5, 2008
Greetings all!
How can I enforce a foreign key constraint when I have two tables each one residing on a different database?
Thanks for your help in advance.
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Jul 20, 2005
Hello,I'm working with a number of databases. I need a way to determine if aforeign key with given name exists and determine what tables andfields are linked to it. Any ideas?I know I can issue the following statement to get a list of the fieldsthat are constrained by a foreign key constraint.SELECT * FROM INFORMATION_SCHEMA.CONSTRAINT_COLUMN_USAGEHow can I get a list of fields pointed to by the constraints?Thanks,WillJoin Bytes!
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Oct 1, 2007
Hello!
I am trying to alter a table adding a column with foreignkey constraint. The table that holds the primary key in that relation has data, so i am not being able to execute the alter statement.
This is the error:
Server: Msg 547, Level 16, State 1, Line 1
ALTER TABLE statement conflicted with COLUMN FOREIGN KEY constraint 'FK_MOPAeroportoICAO_IDMOPAlimentacaoFerroviaTipo'. The conflict occurred in database 'MOP', table 'MOPAlimentacaoFerroviaTipo', column 'IDMOPAlimentacaoFerroviaTipo'.
This is the script:
ALTER TABLE MOPAeroportoICAO
ADD IDMOPAlimentacaoFerroviaTipo [int] DEFAULT 0 NOT NULL
CONSTRAINT [FK_MOPAeroportoICAO_IDMOPAlimentacaoFerroviaTipo] FOREIGN KEY
REFERENCES MOPAlimentacaoFerroviaTipo (IDMOPAlimentacaoFerroviaTipo)
How can i turn of check when i add the foreign key ?
Thanks in advance
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Feb 8, 2007
Hello, I'm having some problems trying to create this foreign key constraint:
ALTER TABLE dbo.t2_demaclie
ADD CONSTRAINT FK03_T2_DEMACLIE FOREIGN KEY (dclPerfilCompania, dclOrdenPedido)
REFERENCES DBO.T2_PEDIDOCLIENTE (cdPerfilCompania, nmOrdenPedido)
Server: Msg 547, Level 16, State 1, Line 1
ALTER TABLE statement conflicted with TABLE FOREIGN KEY constraint 'FK03_T2_DEMACLIE'. The conflict occurred in database 'Comfruta_dllo', table 't2_pedidoCliente'.
I'm sure there's no other constraint with the same name, and there's no othe one with the same columns...
Thanks a lot !!
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Nov 10, 2006
Hi
I am trying to update tables "Table A" & " TableB" with a new value for a particular column1. Now "TableA" contains a foreign key "FK1" defined on it and is referencing another table "Table B" containing the similar column "Column1"
Because of this constraint I was not able to update TableA and TableB. My question is
1) If i wanted to go ahead with this update, what are the possible ways?
2) If only solution is to drop the constraint. Then How do i know the definition for this particular Foreign key, i mean it may refer some columns in Table B. I wanted to know the complete definition of it so that i can rebuild the constraint after the update. Right now i can see only the constraint name when i use sp_help TableA. But how do i know the complete reference made by this foreign key.
Early reply is much appreciated
Thanks!
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