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Query to find Primary and Foreign keys

rsrinivasan
100+
P: 221
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
May 9 '07 #1
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26 Replies


chandu031
Expert
P: 78
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:
Expand|Select|Wrap|Line Numbers
  1. 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'
  2.  
And this is the query for foreign keys:

Expand|Select|Wrap|Line Numbers
  1. 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'
  2.  
May 9 '07 #2

Expert 100+
P: 102
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.

Expand|Select|Wrap|Line Numbers
  1. SELECT * 
  2. FROM SYS.ALL_CONSTRAINTS A , SYS.ALL_CONS_COLUMNS B
  3. WHERE S.OWNER=<owner_name> AND S.TABLE_NAME=<table_name> AND A.CONSTRAINT_NAME=B.CONSTRAINT_NAME
  4.  
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.
May 9 '07 #3

frozenmist
Expert 100+
P: 179
Hi ,

To correct Chandu. you should also have the owner name.
So code becomes
Expand|Select|Wrap|Line Numbers
  1. 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>'
  2.  
Cheers
May 9 '07 #4

chandu031
Expert
P: 78
Hi,

This is the query to get a list of primary keys:
Expand|Select|Wrap|Line Numbers
  1. 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'
  2.  
And this is the query for foreign keys:

Expand|Select|Wrap|Line Numbers
  1. 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'
  2.  

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.
May 9 '07 #5

rsrinivasan
100+
P: 221
Hi,
Thanks for all...
May 9 '07 #6

rsrinivasan
100+
P: 221
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
May 9 '07 #7

Expert 100+
P: 102
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.
May 9 '07 #8

rsrinivasan
100+
P: 221
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
May 9 '07 #9

cpiyush
P: 31
It was quite useful...

Thanks to everyone.

Cheer.
cPiyush.
May 9 '07 #10

Expert 100+
P: 102
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.

Expand|Select|Wrap|Line Numbers
  1. CREATE VIEW EMP_VIEW
  2. AS
  3. SELECT Empno, Name, Salary 
  4. FROM Employee
  5.  
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.
May 9 '07 #11

rsrinivasan
100+
P: 221
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.

Expand|Select|Wrap|Line Numbers
  1. CREATE VIEW EMP_VIEW
  2. AS
  3. SELECT Empno, Name, Salary 
  4. FROM Employee
  5.  
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
May 9 '07 #12

Expert 100+
P: 102
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.
May 9 '07 #13

rsrinivasan
100+
P: 221
Hi,
I understood the real use of Views. Thanks...
May 9 '07 #14

rsrinivasan
100+
P: 221
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
May 9 '07 #15

Expert 100+
P: 102
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
May 9 '07 #16

rsrinivasan
100+
P: 221
Hi,
I create a function in oracle

Expand|Select|Wrap|Line Numbers
  1. create or replace function 
  2. divide(first integer, second integer) return integer is 
  3. begin 
  4.   if first>second 
  5.       return first 
  6.   else 
  7.       return second 
  8. end;
  9.  
But it tells warning as below..

Warning: Function created with compilation errors.

What is the error? Give correct syntex...

Thanks,
Srinivasan r
May 9 '07 #17

debasisdas
Expert 5K+
P: 8,127
check the code
Expand|Select|Wrap|Line Numbers
  1. create or replace function divide(first integer, second integer) return integer is
  2. begin
  3. if first > second then return first;
  4. else return second;
  5. end if;
  6. end;
  7.  
May 9 '07 #18

cpiyush
P: 31
Hi,
I create a function in oracle

Expand|Select|Wrap|Line Numbers
  1. create or replace function 
  2. divide(first integer, second integer) return integer is 
  3. begin 
  4.   if first>second 
  5.       return first 
  6.   else 
  7.       return second 
  8. end;
  9.  
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.
May 9 '07 #19

debasisdas
Expert 5K+
P: 8,127
You had made some basic mistakes

1. Forgotten to add semicolons.
2. Forgotten to add End if.
May 9 '07 #20

debasisdas
Expert 5K+
P: 8,127
It is not compulsary to specify type.

If nothing is specified default type Is IN .

Not specifying the parameter MODE is not an error.
May 9 '07 #21

cpiyush
P: 31
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...:-)
May 10 '07 #22

P: 6
Hi,
The following query will give all the constraints specified on a table belonging to <owner_name> schema.

Expand|Select|Wrap|Line Numbers
  1. SELECT * 
  2. FROM SYS.ALL_CONSTRAINTS A , SYS.ALL_CONS_COLUMNS B
  3. WHERE S.OWNER=<owner_name> AND S.TABLE_NAME=<table_name> AND A.CONSTRAINT_NAME=B.CONSTRAINT_NAME
  4.  
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
Sep 21 '07 #23

P: 2
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.

.
Feb 20 '10 #24

P: 2
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
Feb 20 '10 #25

P: 6
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>
Feb 25 '10 #26

P: 1
Thanks, that was really useful
Jan 5 '12 #27

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