SQL & PL/SQL :: Foreign Key Constraint
Feb 3, 2012
I have a parent table called dept and one child table emp which is referenced on deptno and now both have data . Now i want to truncate the dept table and i have truncated emp table after it when i am trying to truncate dept table then oracle throws a error that is-
"ORA-02266: unique/primary keys in table referenced by enabled foreign keys" ,
but when i tried to delete some records 1 by 1 then these have delete but truncate is not still working. why? if i have 10 millon records.
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Mar 6, 2013
I've successfully created the below two tables (disregard my use of "char" variable type; beyond the scope of my question):
create table Test_req (
Req_ID varchar2(4) not null,
Req_Comment varchar2(50) null
);
create table Test_n_cycle (
Req_ID varchar2(4) not null,
[code].....
Then I successfully performed the two alter statements:
Alter table test_n_cycle
add constraint test_n_cycle_pk primary key (req_id, test_id);
Alter table test_req
add constraint test_req_pk primary key (req_id);
Then tried this freign key reference statement
Alter table test_n_cycle
add constraint
foreign key (req_id) references test_req (req_id)
Error report:
SQL Error: ORA-00902: invalid datatype
00902. 00000 - "invalid datatype"
Is this because req_id is also defined in the Primary key definitions on these two tables, thus making the field not valid for referential constraint definition?
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Jul 10, 2012
I have table EMP & DEPT.
Can you give me sample "check" constraint so that when I enter an EMP (with status='active') without matching DEPT entry, the process will fail?
It will allow to enter EMP with status='inactive' only even if no matching DEPT entry. So foreign_key will not apply.
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Aug 25, 2010
Create table Car
(Car_cd VARCHAR2(5),
Car_Desc VARCHAR2(50)
);
alter table Car
add constraint Car_PK primary key (Car_CD);
INSERT INTO Car (Car_Cd, Car_Desc) VALUES ('CORLA','COROLLA');
Commit;
[code]....
The requirement necessitates a new table to map car to manufacturer. This mapping table may later be expanded to contain other attributes Engine, MPG, etc to hold details specific to a car.But this is in future.
Create Table Car_Mapping_Details
(Car_Cd VARCHAR2(5),
Manufacturer_Cd VARCHAR2(5));
--Primary Key Constraint
ALTER TABLE Car_Mapping_Details
ADD CONSTRAINT Car_Mapping_Details_pk PRIMARY KEY (Car_Cd );
--Not able to create this as Car_cd is already a PK in this table and therefore has Unique Index
ALTER TABLE Car_Mapping_Details ADD CONSTRAINT Car_Mapping_Details_fk1
FOREIGN KEY (Car_Cd)REFERENCES Car (Car_Cd);
[code]....
But in this case the Car_Mapping_Details.Car_cd is itself is a primary key and therefore has Unique index.Although I was able to create foreign key constraint on Car_mapping_details.car_cd column (which is also Primary Key), I was not able to create Foreign Key Index on this column. It gives me Quote:ORA-01408: such column list already indexed.In other words, not creating foreign index for foreign key column lead to table-level lock? Or will the Unique Index in that primary key column be sufficient to avoid table-level lock?
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Dec 25, 2007
i want to get table name, constraint name, constraint type with join processes in string type. this is what i want: alter table tablename add constraint constraintname constrainttype(columnname)
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Nov 7, 2011
if have table primary key in this table empno and another table foreign key is empno and when add in the primary key 5522 how can
5522 in the empno "foreign key" automatic
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Jul 26, 2011
I have an already populated table that refers to a wrong foreign key in another table. I have table abc that has the column fk_id. this column currently refers to column x_id1 in the table abc while it should refer to column x_id2 in xyz. I am trying to replace the data but I guess I miss something in the logic or the right way of doing it:
following is my trial:
create table abc
(
pk_id number(4) primary key,
abc_name varchar2(10),
fk_id number(4)
);
create table xyz
(
x_id1 number(4),
x_id2 number(4),
x_name varchar2(10)
);
commit;
insert all
into abc values (10,'ab1',1)
into abc values (11,'ab2',2)
into abc values (12,'ab3',5)
into abc values (13,'ab4',7)
into abc values (14,'ab5',9)
into xyz values (1,1,'d1')
into xyz values (2,2,'d2')
into xyz values (5,3,'d3')
into xyz values (7,4,'d4')
into xyz values (9,5,'d5')
select * from dual;
commit;
--this following select returns 5 rows
select * from abc, xyz where abc.fk_id = xyz.x_id1;
-- the following update only updates 3 rows and sets the other 2
-- to null!
update abc set fk_id = (select x_id2 from xyz where xyz.x_id1 = abc.fk_id);
commit;
select * from abc;
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Dec 4, 2011
I'm not really sure why oracle is not finding my Foreing Key, I'm creating an easy set of table for a company and I'm declaring all Primary keys and foreing keys as necessary and this is my
CREATE TABLE Items
(ItemID NUMBER(5) NOT NULL,
Description VARCHAR2(30),
ListPrice NUMBER(9,2) NOT NULL,
QtyOnHand Number(5),
ReorderPoint NUMBER(3),
ReorderQty NUMBER(3),
OnBackOrder Number(3),
CONSTRAINT ItemsPK
[Code] ............
There's three sets of inserts the first two successfully inserts the data NO problem but when i try to insert the data on SupplierItems comes as:
ERROR at line 1:
ORA-02291: integrity constraint (jcarter.SUPPLIERITEMSFK2) violated - parent key not found
I looked on the forum and it appears this happens when someone is doing a Insert ALL but this is not my case..
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Mar 13, 2013
You should almost always index foreign keys because they are frequently used in joins. In addition, if you intend to delete or update unique or primary keys on the parent table, you should index the foreign keys to improve the locking of child records.what I don't understand are, I should create index on foreign key column in parent table or child table or both ?
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Sep 6, 2011
Is there any view in oracle which gives the foreign key mapping.
E.g.
Table DEPT has DEPTNO as PK.
Table Emp has DEPTNO as FK to DEPT.DEPTNO.
I can get the information for DEPT table from R_CONSTRAINT_NAME column of all_constraints table.My requirement is to get the the which column of Emp table refers to DEPT.DEPTNO column .
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Sep 1, 2013
Say we have an employee(id_emp) table with a primary key on id_emp. We have also some history tables emp_stuff with columns say (id_emp, dat_event, some_stuff) with primary key id_emp, dat_event.
This means that we have a unique index on (id_emp,dat_event). We also have a foreign key id_emp that references employee(id_emp). When we update id_emp on employee, we still have a lock on emp_stuff. According to this (end of the page) :
Quote:So, in short, with releases prior to Oracle Database 11g Release 1, you will want an index on the foreign key of the child table if you do any of the following:
Update the parent table primary key
Delete from the parent table
Merge into the parent table
So is id_emp in emp_stuff considered as indexed (through the unique index of the primary key) or do we have to add an explicit index
like this CREATE INDEX emp_stuff ON emp_stuff(id_emp) to avoide child table locks?
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May 2, 2012
I am trying to establish PK-FK relationship between 2 tables. Table 1 has VACC_ID as a primary key. Table 2 has VACC_ID and SCH_ID as the primary keys. I am trying to add VACC_ID from Table 2 as a FK to Table 1. This is the code I used
ALTER TABLE Table_1
ADD CONSTRAINT FK_VACC_ID
FOREIGN KEY (VACC_ID)
REFERENCES Table_2(VACC_ID)
I also tried to add it without writing the query and editing the Table 1. By default, I am getting 2 columns(both VACC_ID) in the local column being referenced to the 2 primary keys(VACC_ID and SCH_ID) of table 2. I also uploaded the screeshot of the error, when I run the query.
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Jul 13, 2010
the view from where we can fetch information for a foreign key viz. reference table, referenced columns etc.
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Apr 18, 2013
In my point of view, deferral FK (DFK) are stronger than non-deferral FK (NDFK). In other words, every NDFK can be moved to DFK. Is there a performance issue ?
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Mar 29, 2011
I need to interchange the value which has foreign key depednecy,
For ex: I have a table dept
deptno| dname|dseq|
10 | CS | 1
20 | SC | 2
and in emp table
eno | ename | deptno |
1 |Raj | 10 |
2 |Ram | 10 |
3 |Vip | 10 |
4 |Muk | 10 |
5 |Sn | 20 |
6 |Snj | 20 |
7 |Asj | 20 |
there is a forign key define :
ALTER TABLE emp ADD (
CONSTRAINT rop_fk
FOREIGN KEY (deptno)
REFERENCES dept (deptno));
Now I want to change the deptno from 10 to 20 and 20 to 10 in dept table . So the ouput will be like
deptno| dname|dseq|
20 | CS | 1
10 | SC | 2
when i am deleting that row I am getting error "ORA-02292: integrity constraint (ROP_FK) violated - child record found".IF i am trying to update i am getting unique key contractin failure.
(Even I cannot update the rest of the column values in dept table as it is also having foreign key dependency) i need to put a sql script in production so that it will interchange.
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May 3, 2013
in a table how many foreign keys can we create.
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Jun 21, 2012
Version 10.2.0.4
CREATE TABLE T1 (I INT PRIMARY KEY);
CREATE TABLE T2 (I INT PRIMARY KEY, J INT);
ALTER TABLE T2 ADD CONSTRAINT T2_FK FOREIGN KEY (J) REFERENCES T1(I);Session 1
INSERT INTO T1 VALUES (1);Session 2
INSERT INTO T2 VALUES (1,1);Session 2 hangs. Why ?
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Oct 7, 2010
In my sql developer I have created a table. Created primary keys. Using alter table I have also created the foreign key. Now I need to add one more foreign key to the same table. Do I have to drop the existing foreign key and then create the 2 new foreign keys using the alter table condition or can I retain the existing FK and just use alter table to add another FK.
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Sep 29, 2010
I am working on a new project in OBIEE. I am asked to do the data modeling in the database using oracle sql developer. I have to create the joins based on the requirements. I have the tables created already. But the primary keys for few tables are not defined for few tables. PK-FK joins are also not done properly.
My questions are
(1) If I have to define the primary key for the existing tables can I do that using the alter table command or should I create the table all over again and then define it?
(2) If I have to make the changes in the existing PK-FK joins how do i go about doing that?
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Sep 10, 2010
I have few BDs replicated using Advanced Replication, some tables are read only (Basic Replication) and another ones are Updatable (Advanced Replication).
The infraestucture is Materialized View Replication, my trouble is, I do not know how to should treat the updatable tables that have foreign keys, I read in another FAQs that you should replicate the indexes using the same way to replicate tables (dmbs_repcat.create_master_repobject)
Which is the correct manner to treat the foreign keys with this kind of updatable snapshots,
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Mar 22, 2013
I have a central entity Address. I have other entities that could have many addresses (Organization, Person for eg). The relation between Organization and Address is one to many and the relation between Person and Address is also one to many.When I modelled it, I ended up having two foreign keys in Address (Organization ID and Person ID).The question that is being raised by the client is "As only one of the foreign key would be populated on each record, the other would be null". The client is not comfortable having nullable foreign keys as they won't be able to maintain integrity. One of the requirement is that No orphan records in Address. By modeling the way above, there are chances for having some orphanned records. I tried to explain that this would be controlled by the program to ensure that no orphan records would be there but their question is that what if someone goes directly and enters a record in Address table without any foreign key value (I dont know who would have an insert/update access on the tables other than the dba's).
I am trying to get some pros and cons on using the nullable foreign keys.
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Jul 4, 2013
I have to create six tables as part of my assignment. I have created 5 tables. I am having trouble with the 6th. How can I reference a foreign key to a composite primary key? I have colored red the areas that I think are giving me trouble which is in the 6th table, the Registration Table.
Create Table Student
(
StudentID number (6,0) NOT NULL,
Student_Name varchar2 (20) NOT NULL,
Constraint Student_PK Primary Key (StudentID)
);
Create Table Faculty
(
FacultyID number (5,0) NOT NULL,
Faculty_Name varchar2 (20) NOT NULL,
Constraint Faculty_PK Primary Key (FacultyID)
);
Create Table Course
(
CourseID varchar2 (10) NOT NULL,
Course_Name varchar2 (20) NOT NULL,
Constraint Course_PK Primary Key (CourseID)
);
Create Table Qualified
(
FacultyID number (5,0) NOT NULL,
CourseID varchar2 (10) NOT NULL,
Date_Qualified varchar2 (10) NOT NULL,
Constraint Qualified_PK Primary Key (FacultyID, CourseID),
Constraint Qualified_FK1 Foreign Key (FacultyID) references Faculty (FacultyID),
Constraint Qualified_FK2 Foreign Key (CourseID) references Course (CourseID)
);
Create Table Section
(
Section_No number (5,0) NOT NULL,
Semester varchar2 (7) NOT NULL,
CourseID varchar2 (12) NOT NULL,
Constraint Section_PK Primary Key (Section_No, Semester, CourseID),
Constraint Section_FK Foreign Key (CourseID) references Course (CourseID)
);
Create Table Registration
(
StudentID number (6,0) NOT NULL,
Section_No number (5,0) NOT NULL,
Semester varchar2 (7) NOT NULL,
Constraint Registration_PK Primary Key (StudentID, Section_No, Semester),
Constraint Registration_FK1 Foreign Key (StudentID) references Student (StudentID),
Constraint Registration_FK2 Foreign Key (Section_No) references Section (Section_No, Semester, CourseID),
Constraint Registration_FK3 Foreign Key (Semester) references Section (Section_No, Semester, CourseID)
);
This is the error I am receiving:
Error starting at line 1 in command:
Create Table Registration
(
StudentID number (6,0) NOT NULL,
Section_No number (5,0) NOT NULL,
Semester varchar2 (7) NOT NULL,
Constraint Registration_PK Primary Key (StudentID, Section_No, Semester),
Constraint Registration_FK1 Foreign Key (StudentID) references Student (StudentID),
Constraint Registration_FK2 Foreign Key (Section_No) references Section (Section_No, Semester, CourseID),
Constraint Registration_FK3 Foreign Key (Semester) references Section (Section_No, Semester, CourseID)
)
Error at Command Line:8 Column:104
Error report:
SQL Error: ORA-02256: number of referencing columns must match referenced columns
02256. 00000 - "number of referencing columns must match referenced columns"
*Cause: The number of columns in the foreign-key referencing list is not equal to the number of columns in the referenced list.
*Action: Make sure that the referencing columns match the referenced columns.
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Nov 16, 2012
I have a requirement like below
I have 3 tables (Prospect,customer,user) and I have a contact_dtls table .
In prospect table Prospect_id is the primary like this customer_id in customer table and user_id in the user table
in the contact_dtls table I have a column contact_id and other cols.The contact_id can be from prospect_id,customer_id and user_id in other words we can tell the prospect can be a contact or the customer can be a contact and the user also can be a contact also.
Now the question is "is it possible to maintain primary key and foreign key relationship with this design that means the prospect_id,customer_id and user_id would be the foreign keys to the contact_dtls table.
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Jul 22, 2010
I have to create indexes on foreign key columns ,now if composite index is already there with foreign key column then that will work or i will have to create a single column index.
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Jan 21, 2012
I have an employee table which has a primary key and a self referencing foreign key, as shown here
create table employee (
id not null,
name not null,
department not null,
supervisor_id not null
,constraint constraint_1 primary key (id)
,constraint constraint_2 foreign key (supervisor_id) references employee (id));
Now if i make the primary key composite, as shown below -
create table employee (
id not null,
name not null,
department not null,
supervisor_id not null
,constraint constraint_1 primary key (id, name)
,constraint constraint_2 foreign key (supervisor_id) references employee (id));
Oracle is throwing the following error -
ORA-02270: no matching unique or primary key for this column-list
How can this error be fixed without changing the composite primary key?
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May 29, 2011
I need to implement the foreign key on a column of a table from 2 tables. My requirement is in bellow.
drop table t1;
create table t1 (slno number, acc_no number);
drop table t2;
create table t2 (acc_no number primary key, acc_name varchar2(100));
drop table t3;
create table t3 (acc_no1 number primary key, acc_name1 varchar2(100));
[code]...
It is provided that the values of acc_no in t2 and acc_no1 in t3 are unique.Now it required that while inserting into t1 , the system will check either t2 or t3 tables.
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May 6, 2010
When i load a name such as 'DÂ'Costa' using sql loader, after loading in Oracle it becomes 'D¿Costa'.
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Mar 30, 2011
I am trying to use reference partitioning the parent table records moved using the row movement . but the child table records are not moving below is my sample .
CREATE TABLE ref_parent1 (
table_name VARCHAR2(30),
order_date DATE,
num_rows NUMBER);
INSERT INTO ref_parent1 VALUES ('TEST',SYSDATE,100);
INSERT INTO ref_parent1 VALUES ('TEST1',SYSDATE,1000);
INSERT INTO ref_parent1 VALUES ('TEST2',SYSDATE,1000);
COMMIT;
[code]....
ORA-14652: reference partitioning FOREIGN KEY IS NOT supported
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Oct 17, 2013
I have now created my tables and now I want to populate them with my data but I get errors below is my full sql command. From last time I learned that one foreign key can be implemented in one table and cannot be duplicated to work around this I changed my foreign key as you can see to "fkone" . but why am I getting errors when trying to add information I mean I have not gotten errors in the first two tables so what am I "doing wrong/ not understanding"
CREATE TABLE CUSTOMER (CUSTOMERNAME varchar (25),STREET varchar (25),CUSTOMERCITY varchar (25),CONSTRAINT CUSTOMER_pk PRIMARY KEY (CUSTOMERNAME)); CREATE TABLE DEPOSIT (CUSTOMERNAME varchar (25),BRANCHNAME varchar (25),ACCOUNTNUMBER int,BALANCE decimal (7,2),CONSTRAINT DEPOSIT_pk PRIMARY KEY (ACCOUNTNUMBER)); CREATE TABLE LOAN(CUSTOMERNAME varchar (25),BRANCHNAME varchar (25),LOANNUMBER int,AMOUNT decimal (7,2),CONSTRAINT LOAN_pk PRIMARY KEY (LOANNUMBER)); CREATE TABLE BRANCH (BRANCHNAME varchar (25),BRANCHCITY varchar (25),ASSETS decimal (7,2) ,CONSTRAINT BRANCH_pk PRIMARY KEY (BRANCHNAME)); ALTER TABLE DEPOSITadd
[code]....
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Jan 17, 2013
I've tried to search this out on the forums, but I'm not finding anything useful. Point me to a resource that discusses the performance considerations of deferred foreign key constraints? I'm only interested in foreign keys.
How much of a performance difference does it really make?
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