Query to find Primary and Foreign keys

[rsrinivasan]

Hi,

1. I have some table. But i do not know how to find primary key column, forign key column in that table. Is any procedure or function is available in oracle to find this?.

Thanks,
Srinivasan r

[chandu031]

Hi,

1. I have some table. But i do not know how to find primary key column, forign key column in that table. Is any procedure or function is available in oracle to find this?.

Thanks,
Srinivasan r

Hi,

This is the query to get a list of primary keys:

SELECT * FROM ALL_CONS_COLUMNS A JOIN ALL_CONSTRAINTS C  ON A.CONSTRAINT_NAME = C.CONSTRAINT_NAME WHERE C.TABLE_NAME = <your table> AND C.CONSTRAINT_TYPE = 'P'
 

And this is the query for foreign keys:

SELECT * FROM ALL_CONS_COLUMNS A JOIN ALL_CONSTRAINTS C  ON A.CONSTRAINT_NAME = C.CONSTRAINT_NAME WHERE C.TABLE_NAME = <your table> AND C.CONSTRAINT_TYPE = 'R'
 

[pradeep kaltari]

Hi,

1. I have some table. But i do not know how to find primary key column, forign key column in that table. Is any procedure or function is available in oracle to find this?.

Thanks,
Srinivasan r

Hi,
The following query will give all the constraints specified on a table belonging to <owner_name> schema.

SELECT * 
FROM SYS.ALL_CONSTRAINTS A , SYS.ALL_CONS_COLUMNS B
WHERE S.OWNER=<owner_name> AND S.TABLE_NAME=<table_name> AND A.CONSTRAINT_NAME=B.CONSTRAINT_NAME
 

You can further filter this based upon the constraint type you are interested in. For primary key constraint, include CONSTRAINT_TYPE='P' in the WHERE clause. For foreign key constraint, include CONSTRAINT_TYPE='R' in the WHERE clause.

[frozenmist]

Hi ,

To correct Chandu. you should also have the owner name.
So code becomes

SELECT * FROM ALL_CONS_COLUMNS A JOIN ALL_CONSTRAINTS C  ON A.CONSTRAINT_NAME = C.CONSTRAINT_NAME WHERE C.TABLE_NAME = <your table> AND C.CONSTRAINT_TYPE = 'R' and C.OWNER='<OWNER NAME>'
 

Cheers

[chandu031]

Hi,

This is the query to get a list of primary keys:

SELECT * FROM ALL_CONS_COLUMNS A JOIN ALL_CONSTRAINTS C  ON A.CONSTRAINT_NAME = C.CONSTRAINT_NAME WHERE C.TABLE_NAME = <your table> AND C.CONSTRAINT_TYPE = 'P'
 

And this is the query for foreign keys:

SELECT * FROM ALL_CONS_COLUMNS A JOIN ALL_CONSTRAINTS C  ON A.CONSTRAINT_NAME = C.CONSTRAINT_NAME WHERE C.TABLE_NAME = <your table> AND C.CONSTRAINT_TYPE = 'R'
 

Yes..You will have to add one more filter on the OWNER as the same table names can be used across users. Thks for pointing it out Frozen.

If you want only the column names you can use
SELECT C.COLUMN_NAME, C.POSITION instead of SELECT *

Position is helpful when you have composite keys.

[rsrinivasan]

Hi,
Thanks for all...

[rsrinivasan]

Hi,

Fine. It is working.
What is that table ALL_CONSTRAINTS and ALL_CONS_COLUMNS.

Whether it is System table or anyother?

Thanks,
Srinivasan r

[pradeep kaltari]

Hi,

Fine. It is working.
What is that table ALL_CONSTRAINTS and ALL_CONS_COLUMNS.

Whether it is System table or anyother?

Thanks,
Srinivasan r

These are system views present in SYS schema.

[rsrinivasan]

Hi,
Just now i see it..

What is the difference between Views and Tables. Anything advantage by using Views? When should we use Views?

Thanks..
Srinivasan r

[cpiyush]

It was quite useful...

Thanks to everyone.

Cheer.
cPiyush.

[pradeep kaltari]

Hi,
Just now i see it..

What is the difference between Views and Tables. Anything advantage by using Views? When should we use Views?

Thanks..
Srinivasan r

Views are snapshots of tables. Data is not physically stored in the views. Views reflect the present data in the tables upon which they are created. You can access data from the views in the same way as you access data from tables.

E.g:Say you have a Employee table with the following columns:
Empno Deptno Name Salary
--------- ----------- --------- - --------

You can create a view which contains a subset of these columns.

CREATE VIEW EMP_VIEW
AS
SELECT Empno, Name, Salary 
FROM Employee
 

Now every time you fire a query on the view, the actual query on which the view is built is executed first followed by the query you fired.
A single View can be built upon multiple tables (you can also use JOINs whie creating the views).
I hope this cleared some of your doubts.

[rsrinivasan]

Views are snapshots of tables. Data is not physically stored in the views. Views reflect the present data in the tables upon which they are created. You can access data from the views in the same way as you access data from tables.

E.g:Say you have a Employee table with the following columns:
Empno Deptno Name Salary
--------- ----------- --------- - --------

You can create a view which contains a subset of these columns.

CREATE VIEW EMP_VIEW
AS
SELECT Empno, Name, Salary 
FROM Employee
 

Now every time you fire a query on the view, the actual query on which the view is built is executed first followed by the query you fired.
A single View can be built upon multiple tables (you can also use JOINs whie creating the views).
I hope this cleared some of your doubts.

hi,
Nice. From ur stat I feel that Views are not phisicaly stored in memory. And it is just a Virtual table. Right?

1. Whether it is possible insert or delete records from views?
2. If I insert record in views whether it affects the real table(physical table)?

Why we are using Views instead of Tables directly?

Thanks,
Srinivasan r

[pradeep kaltari]

hi,
Nice. From ur stat I feel that Views are not phisicaly stored in memory. And it is just a Virtual table. Right?

1. Whether it is possible insert or delete records from views?
2. If I insert record in views whether it affects the real table(physical table)?

Why we are using Views instead of Tables directly?

Thanks,
Srinivasan r

Yes you can say views are virtual tables. You cannot insert/delete records from views. To understand the usage of views consider the following:

Suppose 2 ppl (Admin and clerk) access a table. The clerk is authorised only to view (and cant modify the contents of the table) some part of data from the table but the Admin has full access. Now the Admin can create a view containing only the data required for the clerk and allow the clerk to access it.

Also, suppose data is spread out in two tables and you want to see it in a single table. Instead of creating another table to store this data, you can create a view for the same and hence utilize memo in a better way.

[rsrinivasan]

Hi,
I understood the real use of Views. Thanks...

[rsrinivasan]

Hi,
I have another doubt.
How to create user for oracle and assign only some previlliges. For example only to insert recort into the table.

thanks,
Srinivasan r

[pradeep kaltari]

Hi,
I have another doubt.
How to create user for oracle and assign only some previlliges. For example only to insert recort into the table.

thanks,
Srinivasan r

Hi,
Follow the link: http://www.techonthenet.com/oracle/grant_revoke.php

Cheers,
Pradeep

[rsrinivasan]

Hi,
I create a function in oracle

create or replace function 
divide(first integer, second integer) return integer is 
begin 
  if first>second 
      return first 
  else 
      return second 
end;
 

But it tells warning as below..

Warning: Function created with compilation errors.

What is the error? Give correct syntex...

Thanks,
Srinivasan r

[debasisdas]

check the code

create or replace function divide(first integer, second integer) return integer is
begin
if first > second then return first;
else return second;
end if;
end;
 

[cpiyush]

Hi,
I create a function in oracle

create or replace function 
divide(first integer, second integer) return integer is 
begin 
  if first>second 
      return first 
  else 
      return second 
end;
 

But it tells warning as below..

Warning: Function created with compilation errors.

What is the error? Give correct syntex...

Thanks,
Srinivasan r

Execute this query if you are getting compilation errors:-
show errors;
This will list the line number/col number combination & the description of error which you have made in the function definition.

Check your mistakes using this, as I can see one mistake just by reviewing ur code that you have not specifieds the type(IN/OUT) of the arguments passed in the prototype...

Cheer!!!
cPiyush.

[debasisdas]

You had made some basic mistakes

1. Forgotten to add semicolons.
2. Forgotten to add End if.

[debasisdas]

It is not compulsary to specify type.

If nothing is specified default type Is IN .

Not specifying the parameter MODE is not an error.

[cpiyush]

It is not compulsary to specify type.

If nothing is specified default type Is IN .

Not specifying the parameter MODE is not an error.

Oh...Thanks Das...:-)

[Pumuky]

Hi,
The following query will give all the constraints specified on a table belonging to <owner_name> schema.

SELECT * 
FROM SYS.ALL_CONSTRAINTS A , SYS.ALL_CONS_COLUMNS B
WHERE S.OWNER=<owner_name> AND S.TABLE_NAME=<table_name> AND A.CONSTRAINT_NAME=B.CONSTRAINT_NAME
 

You can further filter this based upon the constraint type you are interested in. For primary key constraint, include CONSTRAINT_TYPE='P' in the WHERE clause. For foreign key constraint, include CONSTRAINT_TYPE='R' in the WHERE clause.

Hi all,
the disscusion is very interesting... I would need to know the way to get the FK between two tables, could you help me?
Thank you in advance,
Pumuky

[thelastfrontier]

Here a query which delivers me the TABLE_NAME,COLUMN_NAME to which a foreign key <table>.<column> is pointing (ORACLE 10).
I use the USER system VIEW to get it:

select cc.TABLE_NAME, cc.COLUMN_NAME from USER_CONS_COLUMNS cc WHERE cc.CONSTRAINT_NAME = ( select c.R_CONSTRAINT_NAME from USER_CONS_COLUMNS cc join USER_CONSTRAINTS c on cc.CONSTRAINT_NAME= c.CONSTRAINT_NAME where c.TABLE_NAME = '<table>' and cc.COLUMN_NAME = '<column>' and C.CONSTRAINT_TYPE='R')

Maybe someone knows a shorter query but it works fine for me.

.

[thelastfrontier]

again a USER query for ORACLE 10: all columns (query result 'ID') in a <table> that represent foreign keys and point to 'TABLE'.'COLUMN':

select
ccc.COLUMN_NAME as "ID", ucc.TABLE_NAME as "TABLE", ucc.COLUMN_NAME as "COLUMN"
from
USER_CONS_COLUMNS ucc,
(
select
cc.COLUMN_NAME, c.R_CONSTRAINT_NAME
from
USER_CONS_COLUMNS cc
inner join
USER_CONSTRAINTS c
on
cc.CONSTRAINT_NAME = c.CONSTRAINT_NAME
where
cc.TABLE_NAME='<table>'
and
c.CONSTRAINT_TYPE='R'
) ccc
where
ucc.CONSTRAINT_NAME = ccc.R_CONSTRAINT_NAME

[Madhusmita Biswal]

in order to know the primary key column name and forign key column in a table just execute the query :=

SELECT * FROM ALL_CONS_COLUMNS A JOIN ALL_CONSTRAINTS C ON A.CONSTRAINT_NAME = C.CONSTRAINT_NAME
WHERE C.TABLE_NAME = <table_name>
AND C.CONSTRAINT_TYPE in ('P','R')
and a.owner=<owner_name>
and c.owner=<owner_name>

[karanshah89]

Thanks, that was really useful