I'm using pl sql developer 12.what i want is to add the make the primary key sequential using oracle 12' windows and forms , not by scripting. I can't find out how?.
aslo, how can i make one to one relation between 2 tables (user,role), in user table i added role_id as foreign key; but the relation seem one to many!!!
In Oracle 12c and above, you define that column as identity columns:
CREATE TABLE mytable (
id NUMBER GENERATED ALWAYS AS IDENTITY,
-- other columns ...
);
A #Mureinik already said, in Oracle 12 and higher versions you can define your primary key column as NUMBER GENERATED ALWAYS AS IDENTITY to get a unique sequential value.
To enforce a one-to-one relationship in the database you'd want to have your ROLE_ID column defined as a primary key on one table, and as either a UNIQUE or PRIMARY key on the second table, with a foreign key relationship between the tables. In other words:
CREATE TABLE T1 (ROLE_ID NUMBER
CONSTRAINT PK_T1
PRIMARY KEY
...);
CREATE TABLE T2 (ID_T2 NUMBER
PRIMARY KEY,
ROLE_ID NUMBER
CONSTRAINT T2_U1
UNIQUE
CONSTRAINT T2_FK1
REFERENCES T1(ROLE_ID)
ON DELETE CASCADE,
...);
After the above ROLE_ID will be the primary key on T1, a unique key on T2, and T2.ROLE_ID will be a foreign key to T1.
Best of luck.
what I have done lastly is that i downloaded sql developer 64 w, and from it; I connected with the database then I made the column sequential
Related
I have a problem in oracle and I need help. I have the following query:
1 CREATE TABLE TEST1 (
2 NAME VARCHAR(20)
3 ID VAR(9)
4 PRIMARY KEY(ID)
5 FOREIGN KEY(NAME) References TEST2(ANAME)
6 ON DELETE CASCADE ON UPDATE SET NULL );
If I want to delete line #6 what should i do?
"How I can change the value of primary key and based of that the foreign keys of this pk will change too?"
First, you should never need to do that. Primary keys like this are really just numbers that identify a row, they have no meaning in themselves. It's like asking how you would change the ROWID of a row.
If you must, you could:
Find the foreign keys pointing to this table and disable them with ALTER CONSTRAINT myconstraint DISABLE
Update your primary table and catch the new id value with UPDATE test1 SET id = mysequence.NEXTVAL WHERE id = :oldid RETURNING id INTO :newid, assuming it's set by a sequence.
Update the ids in your other tables with the new id.
Reenable your constraints.
Note that altering constraints is DDL and will do an implicit commit and this approach will leave your tables unprotected by the foreign key constraints.
A second approach would be to:
Insert a new row in the primary table and catch the new id.
Update the id in the foreign tables with the new id.
Delete the old row in the primary table.
Now that I think about it, that second approach seems better to me. No DDL and it just seems cleaner.
I have some problems with Oracle Foreign Composite keys. I have an application that is somewhat big (you know, 5000+ tables, that kind of thing) and we store some 'static' (it actually can change) data into some set of tables. This data is referenced by a lot of the tables through the database, so it worked like this:
TABLE StaticData
ID(PK) Data
1 StaticData1
2 StaticData2
...
n StaticDataN
TABLE TypicalTable
ID(PK) StaticDataID(FK to StaticData)
1 1
2 1
3 7
4 2
...
n n
And all was well in Wonderland.
But some changes of spec, and some meetings with the client after, we were tasked with having different 'versions' of the data ready to replace the static data when some time arrives. Last part was easy, we can create jobs that will check every day/week for a date and change the data, but we will have to maintain older and newer versions of the data... in the same table. So now StaticData looks like:
TABLE StaticData
ID(PK) Data KickInDate(Also PK)
1 StaticData1.1 01/01/1900
1 StaticData1.2 10/07/2014
1 StaticData1.3 12/12/2015
2 StaticData2.1 01/01/1900
...
n StaticDataN.1 01/01/1900
And of course all integrity reference has gone off the board. And of course, since I cannot put a UNIQUE constraint in the ID, I cannot keep the foreign keys.
I have searched the net for a solution for this (less restrictive kind of foreign keys) and most of the time the solution is to use triggers checking BEFORE INSERT|UPDATE|DELETE
But that will be kind of a very, very, very big job.
So I ask, Do I have other solutions?
Is there any way to tell Oracle to reference another column of another table even thought is not UNIQUE? (it will definitely be NOT NULL).
Primary keys in Oracle can have duplicates. Primary keys can be built with non-unique indexes and existing values can be excluded by creating the constraint with NOVALIDATE. It is a rarely used feature, will confuse people, and is not a clean solution. But in the real world sometimes data isn't clean and there's no time for the perfect solution.
Sample schema and data.
create table staticData
(
id number not null,
data varchar2(100),
constraint staticData_pk primary key (id)
);
create table typicalTable
(
id number not null,
staticDataID number,
constraint typicalTable_pk primary key (id),
constraint typicalTable_fk foreign key (staticDataID)
references staticData(id)
);
insert into staticData values (1, 'StaticData1');
insert into staticData values (2, 'StaticData2');
insert into typicalTable values(1, 1);
insert into typicalTable values(2, 1);
Process to drop constraints, add duplicate data, and re-enable constraints.
--Drop constraints.
alter table typicalTable drop constraint typicalTable_fk;
alter table staticData drop constraint staticData_pk;
--Add semi-duplicate data.
insert into staticData values (1, 'StaticData1.2');
--Use a non-unique index to build a NOVALIDATE primary key.
create index staticData_pk on staticData(id);
alter table staticData add constraint staticData_pk primary key (id) novalidate;
alter table typicalTable add constraint typicalTable_fk foreign key(staticDataID)
references staticData(id);
No, the target column(s) must be unique, that's the whole idea. However, you can propagate an additional version column from StaticData to TypicalTable:
CREATE TABLE StaticData (
id NUMBER,
version NUMBER,
col1 ... coln,
PRIMARY KEY (id,version)
);
CREATE TABLE TypicalTable (
StaticDataID NUMBER,
version NUMBER,
colx ... coly,
FOREIGN KEY (StaticDataID, version) REFERENCES StaticData(id, version)
);
There is a requirement in our application to create the unique primary key which depend on the value of another unique column (ERROR_CODE). But our application is in a geo active active environment (have several active databases which are synchronized using another program).
Therefore even-though we have a unique constraint on this ERROR_CODE field, there is a possibility that each database has a row with a different PK for the same ERROR_CODE. During the database synchronization, this is a problem, because there are some child tables which has the PK stored in one DB and other rows contain the PK stored in other DB. Because of the unique constraint of ERROR_CODE, sync process cannot move both rows to each database (which is also not a good thing to do).
So there is a suggestion to use the hash of the ERROR_CODE field as the PK value.
I would like to know whether we can define a function based Primary key in oracle?
If PK field is "ID",
"ID" should be equal to ora_has(ERROR_CODE).
Is it possible to define the primary key like that in oracle?
In Oracle 10 you cannot do this, but in Oracle 11 you can. You have to create a virtual column, such columns can be used also as primary key:
ALTER TABLE MY_TABLE ADD (ID NUMBER GENERATED ALWAYS AS (ora_has(ERROR_CODE)) VIRTUAL);
ALTER TABLE MY_TABLE ADD CONSTRAINT t_test_pk PRIMARY KEY (ID) USING INDEX;
Not able to create /find the logic to apply FK on a column in child table referencing a column from composite PK of parent table.
create table product(prod_id number,
prod_name varchar2(20),
price number,
constraint PK12 primary key(prod_id,prod_name));
Table created.
create table purchase(prod_id number,
purchase_price number,
constraint FK12 foreign key(prod_id) references product(prod_id));
create table purchase(prod_id number,
purchase_price number,
constraint FK12 foreign key(prod_id) references product(prod_id))
ERROR at line 1:
ORA-02270: no matching unique or primary key for this column-list
Kinldy suggest how i can incorporate this logic.
Thanks.
You can't.
As the error says there's no matching primary key for that column list; you must have one. You have three options:
Remove PROD_NAME from the primary key of PRODUCT. On the face of it this seems like the logical solution, if this is not required in order to make the primary key unique.
Add PROD_NAME to the PURCHASE table.
Create a unique index on PURCHASE.PROD_ID. This seems excessive if it would be a primary key candidate anyway.
I suspect that this is not unique to Oracle. Considering you have a composite primary key in the referenced table, that implies that only one of the columns comprising the composite key is not enough to uniquely identify the record in that table. Therefore, it's impossible to reference only a single column of the primary key in a foreign key relationship that's one-to-many (e.g. one record in the referenced table can have many records in the referencing table--the one with the FK). However, if the relationship to be established is many-to-many, this may be possible.
HTH.
i have table. which has 5 columns in that 3 of the columns makes primary key combinations.
table (cola, colb, colc, cold, cole)
i want to update one of the column which is in primary key group. how to do that?
its giving primary key constraint error.
You should disable do your modification an re enable the constraints that are linked to your primary key. (Unique, non-null, etc...)
Take a look at this website
If you really need to maintain uniqueness over these three columns, then define a unique constraint on the three columns making up your current PK, and then define a new surrogate primary key column.
Just in case you have to change the referncing data too.
First note contrary to MS-SQL-Server there is no foreign Key contraint with on update cascade see How to create a Foreign Key with “ON UPDATE CASCADE” on Oracle?.
Than I would insert a new row in the primary table, update the referencing table to reference the new row and finally delete the original primary row.