Foreign key constraint on multi-column primary key accepts 1 empty column!?

Hi, we have a reference table with a two-column primary key. In the child table there is a non-mandatory foreign key constraint to this table. So if both child columns are null it's ok too. But now we see that if one of the two child table columns that build up the foreign key is null, the other column can have any (non-existant in the master-tabel) value you like!? That does not make sense.
Can anyone explain this to me???
Regards, Paul.

Paul, I believe that this is in accordance to the ANSI SQL standard requirement for the treatment of nulls in a multi-column FK. In any case Oracle specifically states this is the way FK work From the 10 Concepts manual, Ch 21 Data Integrity, topic Nulls and Foreign Keys:
The relational model permits the value of foreign keys either to match the referenced primary or unique key value, or be null. If any column of a composite foreign key is null, then the non-null portions of the key do not have to match any corresponding portion of a parent key. <<HTH -- Mark D Powell --

Similar Messages

Does a foreign key have to be a primary key

Hey all.I was checking on the database code written by sambapos.To my surprise, I found a foreign key that is not a primary key anywhere.
Is that possible?
If, so why?
I am really astonished.

Limitations and Restrictions
A foreign key constraint does not have to be linked only to a primary key constraint in another table; it can also be defined to reference the columns of a UNIQUE constraint in another table.
When a value other than NULL is entered into the column of a FOREIGN KEY constraint, the value must exist in the referenced column; otherwise, a foreign key violation error message is returned. To make sure that all values of a composite foreign key constraint
are verified, specify NOT NULL on all the participating columns.
FOREIGN KEY constraints can reference only tables within the same database on the same server. Cross-database referential integrity must be implemented through triggers. For more information, see
CREATE TRIGGER (Transact-SQL).
FOREIGN KEY constraints can reference another column in the same table. This is referred to as a self-reference.
A FOREIGN KEY constraint specified at the column level can list only one reference column. This column must have the same data type as the column on which the constraint is defined.
A FOREIGN KEY constraint specified at the table level must have the same number of reference columns as the number of columns in the constraint column list. The data type of each reference column must also be the same as the corresponding column in the column
list.
The Database Engine does not have a predefined limit on either the number of FOREIGN KEY constraints a table can contain that reference other tables, or the number of FOREIGN KEY constraints that are owned by other tables that reference a specific table.
Nevertheless, the actual number of FOREIGN KEY constraints that can be used is limited by the hardware configuration and by the design of the database and application. We recommend that a table contain no more than 253 FOREIGN KEY constraints, and that it
be referenced by no more than 253 FOREIGN KEY constraints.
FOREIGN KEY constraints are not enforced on temporary tables.
If a foreign key is defined on a CLR user-defined type column, the implementation of the type must support binary ordering. For more information, see
CLR User-Defined Types.
A column of type varchar(max) can participate in a FOREIGN KEY constraint only if the primary key it references is also defined as type
varchar(max).
Read this article
http://msdn.microsoft.com/en-us/library/ms189049.aspx
Regards, Ashwin Menon My Blog - http:\\sqllearnings.com

In JDO, can a foreign key be part of a primary key?

Hi, it's possible to have a foreing key a part of a primary key in JDO?
The JDO checker is complaining about that. It says "Primary key field 'person' cannot declare relationship".
For example, if I have an entity 'Person' (id, name) and and entity 'Pet' (name, age). Can I have the primary key of 'Person' (id) as a foreign key in 'Pet', and can I have a compound primary key in 'Pet' with 'name' and 'id' as the compound key?
Thanks in advance.
Rafael

Hi Dino,
First of all, thank you very much for your answer.
I read the article, but the solution proposed isnt clear to me. The theorical solution is: You'll have to map the foreign key columns to individual simple fields in your class rather than a single related object. At runtime, you can use the values of these fields to construct an application identity instance, which you can then use to fetch the related object
I dont understand the second sentence how would I fecht the related object at runtime?
Did you try it? Could you please send me an example? I change the type of my attributes to primitive types, and I left my .jdo and .map files as if those attributes were only primary keys how would I specify the relation at runtime with the other table?
My email is [email protected], I would really appreciate your help.
Best regards,
Isidro

Violation of PRIMARY KEY constraint . Cannot insert duplicate key in object

hi i am using SQL Server, when i try to insert data from my jsp page it is inserting the data double time and when i try to submit for second time it is showing the following error.
Violation of PRIMARY KEY constraint 'PK_EMPLOYEE'. Cannot insert duplicate key in object 'EMPLOYEE'.
I didnt set identity for primary key. If i try to set identity to true then it is allowing data to submit only if i uncheck my primary key column in cached row set. And if i uncheck that primary key element then i can not retrieve the data by edit button. So how to solve this problem.
Please any help would be appreciated.
Thank You in Advance.

Hi,
I am providing support to one of our clients, where we have jobs scheduled to load the data from the tables in the source database to the destination database via SSIS packages. The first time load is a full load where we truncate all the tables in the destination
and load them from the source tables. But from the next day, we perform the incremental load from source to destination, i.e., only modified records fetched using changed tracking concept will be loaded to the destination. After full load, if we run the incremental
load, the job is failing with the error on one of the packages "Violation of PRIMARY KEY constraint. Cannot insert duplicate key in object '<tablename>'. The duplicate key value is <1234>, even though there are no duplicate records. When we
try debugging and running the failing package, it runs successfully. We are not able to figure out why the package fails and when we run the next day it runs successfully. Request you to help me in this regard.
Thank you,
Bala Murali Krishna Medipally.
I suspect you are trying to insert modified records instead of updating.

SSIS - "Violation of PRIMARY KEY constraint. Cannot insert duplicate key in object ' tablename '. The duplicate key value is 1234 . Though there are no duplicate records.

Hi,
I am providing support to one of our clients, where we have jobs scheduled to load the data from the tables in the source database to the destination database via SSIS packages. The first time load is a full load where we truncate all the tables in the destination
and load them from the source tables. But from the next day, we perform the incremental load from source to destination, i.e., only modified records fetched using changed tracking concept will be loaded to the destination. After full load, if we run the incremental
load, the job is failing with the error on one of the packages "Violation of PRIMARY KEY constraint. Cannot insert duplicate key in object '<tablename>'. The duplicate key value is <1234>, even though there are no duplicate records. When we
try debugging and running the failing package, it runs successfully. We are not able to figure out why the package fails and when we run the next day it runs successfully. Request you to help me in this regard.
Thank you,
Bala Murali Krishna Medipally.

Hi,
I am providing support to one of our clients, where we have jobs scheduled to load the data from the tables in the source database to the destination database via SSIS packages. The first time load is a full load where we truncate all the tables in the destination
and load them from the source tables. But from the next day, we perform the incremental load from source to destination, i.e., only modified records fetched using changed tracking concept will be loaded to the destination. After full load, if we run the incremental
load, the job is failing with the error on one of the packages "Violation of PRIMARY KEY constraint. Cannot insert duplicate key in object '<tablename>'. The duplicate key value is <1234>, even though there are no duplicate records. When we
try debugging and running the failing package, it runs successfully. We are not able to figure out why the package fails and when we run the next day it runs successfully. Request you to help me in this regard.
Thank you,
Bala Murali Krishna Medipally.
I suspect you are trying to insert modified records instead of updating.

Two column primary keys

Hello,
I am using two columns for my primary key. However when I crate a report and form pages, it doesn't work. The report page shows up but when I click on the edit icon next to each record it gives an error message.

Zahid Khan wrote:
Hi User (very common name!),
In the following simple page I am using empno and hiredate columns as primary key:
http://apex.oracle.com/pls/otn/f?p=9396:10
It would be easier to help you if you set up an example on OTN.
Thanks,
ZahidDear Zahid,
I looked at the application example you provided and the way the trigger ensures the trunc function is called on the date field before writing it to the db table, so the date retrieved from the db looks exactly the same as the date inserted.
CREATE TABLE "EMP_DATE_KEY"
(     "EMPNO" NUMBER,
     "ENAME" VARCHAR2(10),
     "HIREDATE" DATE,
     "SAL" NUMBER,
     "DEPTNO" NUMBER,
     CONSTRAINT "PK_EMP_DATE_KEY" PRIMARY KEY ("EMPNO", "HIREDATE") ENABLE
CREATE OR REPLACE TRIGGER "BIUD_EMP_DATE_KEYS"
before insert on emp_date_key
for each row
begin
select nvl(max(empno),0)+1, trunc(sysdate)
into :new.empno, :new.hiredate from emp_date_key;
end;
ALTER TRIGGER "BIUD_EMP_DATE_KEYS" ENABLE
Line: --------
However the database I am dealing with has not used the trunc function when creating the date field values and the primary key, by the way this db is very old and has a lot of data in it.
any suggestions?
Thanks,
user

Remove the primary key constraint and add new primar key to the table.

Hi all,
We had a design plan to remove a primary from the table on column X(VARCHAR) and add a new primary key on column Y(sequence)(dimensional table). Instead, I am planning to create a unique index on the column Y (I am referring column Y in my Fact table).
I am using the column Y while joining the dimensional and fact table. Now, my question is.
Is the retrieval will be faster if I make column Y as primary key or Is it the performance same if I create a unique index on it ?
Note: Both column X and Y in dimension table are unique and not null. Don't want to alter the existing system hence want to create unique index .
Please suggest.
Thanks and Regards
Nagaraja Akkivalli

When you define a column as Primary key column you give certain information to Oracle that i can use when accessing that table. And similarly when you say a column as Unique Key column you give certain details to oracle that i can use when accessing that table.
So it is up to you to decide if the what that column is meant to do. And decide based on that.
For example a Unique column can have NULL values. But a primary key cannot have NULL value. This piece of information can be critical to oracle to generate the best plan.

Key in View for two primary keys tables

Hi
I have some view joining LIKP and LIPS:
LIKP -   Primary Key MANDT, VBELN
LIPS -   Primary Key MANDT, VBELN, POSR
The Key for the LIKP-LIPS View is:
MANDT      LIKP
VBELN       LIKP
MANDT_I    LIPS
VBELN_I    LIPS
POSNR_I   LIPS
So, for that Key, if i need to acces a specify LIPS detail record , must i fill all the keys in the where (filling VBELN twice) like this:
WHERE VBELN = vbvalue AND VBELN_I = vbvalue AND POSNR_I = posvalue ?
How must i make the Select for acces this View using its Key ?
Regards
Frank

Hi
Just as I said:
SELECT SINGLE * FROM Z<VIEW> WHERE VBELN = <VBELN>
                                                            AND POSNR_I = <POSNR>.
Anyway it's should be better you correct the view deleting the field MANDT_I, VBELN_I, if you can't, I believe the select above works fine.
VIEW FIELDS:
View Field Table Field Key
MANDT LIKP MANDT Yes
VBELN LIKP VBELN Yes
<b>MANDT_I LIPS MANDT Yes <----- WRONG
VBELN_I LIPS VBELN Yes      <----- WRONG</b>
POSNR_I LIPS POSNR Yes
ERNAM LIKP ERNAM
ERDAT LIKP ERDAT
VKORG LIKP VKORG
PSTYV_I LIPS PSTYV
MATNR_I LIPS MATNR
WERKS_I LIPS WERKS
LGORT_I LIPS LGORT
By this defintion the field MANDT and VBELN are only twice, but it doesn't mean the record is double in the VIEW.
So it you have the delivery 100 with 3 items in the client 200, in the view you'll see:
Record 1: MANDT   = 200
               VBELN    = 0000000100
               MANDT_I = 200
               VBELN_I = 0000000100
               POSNR_I = 000010
Record 2: MANDT   = 200
               VBELN    = 0000000100
               MANDT_I = 200
               VBELN_I = 0000000100
               POSNR_I = 000020
Record 3: MANDT   = 200
               VBELN    = 0000000100
               MANDT_I = 200
               VBELN_I = 0000000100
               POSNR_I = 000030
Max

ORA-12014: table 'DBA' does not contain a primary key constraint

Hai
when implementing basic replication i got the below error.
ORA-12014: table 'DBA' does not contain a primary key constraint
I was wondering primary key is enable at remote table
Any idea about this
Regards
mohan
I am giving below example
AT master site
global_names=false in init.ora file
sql>create table dba(no number primary key);
table created
and create snapshot log
sql>create snapshot log on m1;
materilized view created
AT SNAPSHOT SITE
1.Create service using net8 stiring name like n1
2.create database link
sql>create public database link m3 connect to system identified by manager using 'n1';
Database link created.
3.when creating snapshot site i got below error
SQL> create snapshot snap1 refresh fast start with sysdate next sysdate+1/(24*60
*60) as select * from dba@m3;
create snapshot snap1 refresh fast start with sysdate next sysdate+1/(24*60*60)
as select * from dba@m3
ERROR at line 1:
ORA-12014: table 'DBA' does not contain a primary key constraint

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Database Adapter Merge with char/varchar primary key

Hi guys,
It seems as though merge statements in BPEL database adapters do not work if the primary key of the table contains a char/varchar. This is in Jdeveloper 10.1.3.4.0
If I create the table below:
create table test_merge (
id        number primary key,
text      varchar2(255)
);Then the merge operation will update and insert as expected. However, if I create the same table but with id as a char/varchar, then the merge statement will never update.
It seems like it never finds a record with the same id (if it is a char/varchar), and always attempts to insert, which results in unique key constraint errors for the primary key column.
Has anyone else encountered this issue and found a way to get the merge statement to work correctly? I can obviously perform the select myself, and then conditionally update/insert, but I would prefer the merge to work as expected.
Thanks

After investigating further, it seems that even a database adapter select is not working correctly. Consider the following table:
create table test_merge (
id        varchar2(255) primary key,
text      varchar2(255)
);And I have inserted a record with id = "1" and text="abc"
If I create a BPEL process and add a database adapter (with only the select checkbox ticked) with the following SQL:
SELECT ID, TEXT FROM TEST_MERGE WHERE (ID = #id)If I invoke this adapter, passing in "1" as the id, then a record is returned, with the correct text (i.e. "abc") BUT the id returned is "-9900000000000000000000000000"
Can anyone explain why this is happening?

Modifying column adding primary key constraint

how can we alter a table and modify a column and add a primary key constraint to it??

987018 wrote:
can't we add a primary key constraint using the modify command?If the column already exists, and ther is no existing primary key, then
SQL> create table t (id number, descr varchar2(10));
Table created.
SQL> alter table t modify (id not null primary key);
Table altered.If the column does not yet exist and ther is no primary key then:
SQL> create table t1 (descr varchar2(10));
Table created.
SQL> alter table t1 add (id number not null primary key);
Table altered.John

Primary key foreign key dependencies

hi gems...
I have a table with composite primary key (COL1, COL2)..
create table TABLE1 (COL1, COL2);
alter table TABLE1 add constraint PK_TABLE1 primary key (COL1, COL2);
Now i am trying to make another table which will refer to the COL1 of the first table.
create table TABLE2 (COL3, COL4);
alter table TABLE2 add constarint FK_TABLE2 (COL3) references TABLE1(COL1);
but it is failing with "no matching unique or primary key" error.

You have created a composite primary key, so there must be composite foreign key that references the composite primary key. You cannot create Foreign key that references to single column of the composite primary key.

Join 2 tables which are not related with any primary-foriegn key constraint

Hello,
How to join 2 tables which are not related with any primary key foreign key constraint.
Ex.Consider Table A has 5 columns->A_ID,A_Name,A_Address,A_City,A_Pin(Total 10 rows)
Table B has 5 columns->B_ID,B_Name,B_Adress,B_City,B_City(Total 30 rows)
From both the table i want the data,which i need to use in curosr to display finally as "Address Label".
Both the table are entirely different,but there can be some names of Table A which may come in Table B also,if the name,address and city is also same.That means same person in both the table.
So finally i want total number of distinct records(distinct data of Table A which is not in B+all the data of table B) to come under Address Label.
How can i write the select query for this condition?
Thanks
Swapna

Hi, Swapna,
user11018268 wrote:
Hello,
How to join 2 tables which are not related with any primary key foreign key constraint.
Ex.Consider Table A has 5 columns->A_ID,A_Name,A_Address,A_City,A_Pin(Total 10 rows)
Table B has 5 columns->B_ID,B_Name,B_Adress,B_City,B_City(Total 30 rows)
Both the table are entirely different,but there can be some names of Table A which may come in Table B also,if the name,address and city is also same.That means same person in both the table.I think you want a UNION, not a join.
If you have 10 rows in table_a, and 30 rows in table_b, then
SELECT       A_ID,          A_Name,     A_Address,     A_City,     A_Pin
FROM      table_a
UNION
SELECT       B_ID,          B_Name,     B_Adress,     B_City,     B_City
FROM      table_b
ORDER BY           2,               4
;will produce up to 40 rows; 40 if there are no duplicates. (UNION implies DISTINCT.)
The corresponding column types should be similar, if not exactly the same.
There's no problem if A_Name is VARCHAR2 (50) and B_Name is CHAR (30).
However, there will be a problem if A_ID is a NUMBER and B_ID is a TIMESTAMP.
You must have the same number of columns in all branches of the UNION.
If you want an ORDER BY clause, put it at the very end, after the last branch of the UNION.
You can use positional notation (where 2 means the 2nd column) like I did, or you can use names from the first prong of the UNION (such as A_Name).
From both the table i want the data,which i need to use in curosr to display finally as "Address Label".
So finally i want total number of distinct records(distinct data of Table A which is not in B+all the data of table B) to come under Address Label.I'm not sure what your mean about "Address Label".
Whenever you have a question, post a little sample data (CREATE TABLE and INSERT statements, relevant columns only) from all tables, and the exact results (formatted) that you want from that data.
You can concatenate all 5 columns into one VARCHAR2 column, if you want to.
You'll probably want to use RPAD (or simillar functions) to make the output line up nicely.
If any of the columns are not strings, use TO_CHAR to make string versions of them.
For example:
SELECT TO_CHAR (A_ID, '9999999')
     || '   '          -- leave a little space between the left-justified a_id and the right-justified a_name
     || RPAD (A_Name, 25)
     || RPAD (A_Address, 50)
     ...Edited by: Frank Kulash on Nov 14, 2009 10:11 AM

APEX don't allow modify rows in columns which are Primary Key ?

I have tables:
http://img508.imageshack.us/my.php?image=21269582oe8.jpg
book(id_book - "Primary Key", title, year); book_author(id_book - "Primary Key", id_author - "Primary Key"); author(id_author - "Primary Key", name)
I have created a new page -> Form -> Tabular Form for table 'author' because I would like to add new authors, modify and delete. During creating this page I have choosen column 'id_author' as 'primary key column 1' and everything is OK (I can't modify column 'id_author' - this column is autoincrement and I can modify column 'name').
BUT I have also created a new page -> Form -> Tabular for table 'book_author' because I would like to write numbers as id_book and id_author, modify and delete them (so add relations between tables: book, book_author and author). During creating this page I have choosen column 'id_book' as 'primary key column 1' and 'id_author' as 'primary key column 2'. And on website I can't modify (edit) these fields. And I can't also add new row because I see in each column in new row: (null).
http://img444.imageshack.us/my.php?image=11324615yk9.jpg
APEX don't allow modify rows in columns which are Primary Key ? This is stupid....... What can I do ?
Edited by: user10731158 on 2008-12-20 11:40

Single-column and non-meaningful so you never want to update them. In the case of your example, you would need to add an ID column to the book_author intersection table. Honestly, I was so blown away (and pleasantly surprised) by the lack of rebuttal and the "thx" that I went ahead and put together an example of how I would define the book_author table:
create table book_author
   (id varchar2(32),
    book_id varchar2(32),
     author_id varchar2(32),
     modified_on     date,
     modified_by varchar2(255),
     constraint book_author_pk primary key (id),
     constraint book_auth_book_fk foreign key (book_id) references books(id),
     constraint book_auth_author_fk foreign key (author_id) references authors(id)
create unique index book_author_uq on book_author (book_id,author_id)
create or replace trigger biu_book_author before insert or update on book_author
for each row
begin
     if inserting then
          :new.id := sys_guid();
     end if;
     modified_on := sysdate;
     modified_by := nvl(v('APP_USER'),user);
end;
/Good luck,
Tyler

Generated Script fails when attempting to drop Foreign Key Constraint

I made some changes to my database. I used the generate script process to generate a drop and create script to these tables. The generated script first ran Alter Table Drop Constraints to drop the Foreign Key constraints and then did Drop tables
and then did create table to construct the script with the proper changes.
However, when we attempted to run the script, all of the Drop constraint statements failed reporting that there was no such constraint. Then the drop table scripts failed because of the existence of the very foreign key constraints that SQL Server
had just stated did not exist.
BOL states that the statement "DROP { [ CONSTRAINT ] constraint_name | COLUMN column_name } " is "Used in a CHECK, FOREIGN KEY, UNIQUE, or PRIMARY KEY constraint." So why couldn't I drop those specified Foreign
Key constraints in a script generated by SQL Server itself.
Edward R. Joell MCSD MCDBA

Are you sure there are no Constraints on other tables which are causing your issue?
If a foreign key from table abc refences table def it will cause the drop to fail.
If your script is already attempting to drop such constraints, have you checked that they are dropping from the correct table (and not the table that would be the target of the drop)?
I discovered two things yesterday and one thing today about generated scripts.
When you generated a script to drop and create a set of tables and you mark it to include foreign keys, the generated script will first create a set a scripts to drop the foreign keys , then will create a set of statements for each table that will,
first, again drop the same foreign keys that it did earlier, then drop the table. If there is no "if exists" statement for each statement, the drop constraint will fail.
The script generated by the generate scripts wizard, even when you set the Drop and Create option in the advanced tab, unlike the scripts generated when you right click a table and select Drop and Create from the context menu, does not by default create
an "If Exists" statement before the attempt to drop anything.
You can make the generate Scripts wizard generate an "if exists" statement by changing the "Include if NOT EXISTS" option on the advanced tab to true. However, while the script generator will find all of the foreign keys that show that
table as the parent_id, it will not show the FK constraints on tables which are not being dropped and created. Nor can you find them by querying the sys.foreign_keys view using the standard type of Foreign Key "If Exists" statement because
it would do a query like
SELECT *
FROM sys.foreign_keys
WHERE object_id = OBJECT_ID(N'[dbo].[FK_prc_ContractSubLines_prc_PRSubLines]')
AND parent_object_id = OBJECT_ID(N'[dbo].[prc_ContractSubLines]')
And the script generator does not care even if you show an option like "Generate Scripts For Dependent Objects", it will not generate a drop script for the foreign constraints on other tables that reference your table. I have not even found
a way to get back the results of a query on the sys.foreign_keys view that will show those keys that reference your table. The only thing I been able to do is to open the table in design and check out the list of relationships in your table and see open each
relationship and see which table is the "foreign key table" rather than the primary key table. This will make writing drop and create scripts very very long and tedious. As you would have to create addional Alter tables scripts to do a drop
and create foreign keys on each table referencing yours and manually place them into your scripts at correct locations. This is almost as bad as the Oracle SQL Developer's generate script results which (at least in 2010) so screws up the order of the generated
script that it is trying to create foreign keys on tables it has not created yet.
So Patrick I see that you thought about the foreign keys on other tables. I wish I had read your post before spending the morning troubleshooting this issue based on this morning's script that ran and crashed embarrassingly.
I would like to know if someone has a query to reveal all of the foreign keys that reference your table from another table using the sys views. As it is I have to open each table in design to get a list of FKs that reference it.
Edward R. Joell MCSD MCDBA

Foreign key constraint on multi-column primary key accepts 1 empty column!?

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