ORA-02437: cannot validate <name> - primary key violated - sql

Question

I have a table:
CREATE TABLE MY_TABLE (
MY_ID NUMBER NOT NULL,
COLUMN_1 NUMBER,
COLUMN_2 NUMBER
);
ALTER TABLE MY_TABLE ADD CONSTRAINT PK_FOO PRIMARY KEY (MY_ID);
at a later point, when executing the following sql, I get an error:
ALTER TABLE MY_TABLE DROP PRIMARY KEY DROP INDEX;
ALTER TABLE MY_TABLE ADD CONSTRAINT PK_FOO PRIMARY KEY (MY_ID)
ORA-02437: cannot validate PK_FOO - primary key violated
My table only contains 3 entries all with a different primary key which is also not null.
Anyone has an idea what this could be?
Thanks,
Peter

Answer 1

My table only contains 3 entries all with a different primary key which is also not null.
You must forgive a certain amount of scepticism on our part. Because that error definitely indicates a duplicate value.
What you need to do is use the exceptions clause. This will show you the ROWIDs of the records which are violating your constraint. You may need to create the target table: by default the script creates a table called EXCEPTIONS:
SQL> ALTER TABLE MY_TABLE ADD CONSTRAINT PK_FOO PRIMARY KEY (MY_ID);
ALTER TABLE MY_TABLE ADD CONSTRAINT PK_FOO PRIMARY KEY (MY_ID)
*
ERROR at line 1:
ORA-02437: cannot validate (APC.PK_FOO) - primary key violated
SQL> #%ORACLE_HOME%\rdbms\admin\utlexpt1.sql
Table created.
SQL> ALTER TABLE MY_TABLE ADD CONSTRAINT PK_FOO PRIMARY KEY (MY_ID)
2 exceptions into exceptions
3 /
ALTER TABLE MY_TABLE ADD CONSTRAINT PK_FOO PRIMARY KEY (MY_ID)
*
ERROR at line 1:
ORA-02437: cannot validate (APC.PK_FOO) - primary key violated
SQL> select * from exceptions
2 /
ROW_ID OWNER TABLE_NAME CONSTRAINT
------ ----- ---------- ----------
AABQXcAAEAAAXUPAAD APC MY_TABLE PK_FOO
AABQXcAAEAAAXUPAAB APC MY_TABLE PK_FOO
SQL>
Edit
You need to figure out what is different between your install code and the simplification you posted here. The chances are you have one or more INSERT statements which are accidentally executed more than once while the constraint is not in force. Adding the EXCEPTIONS INTO clause to your code might help you track it down.

Answer 2

from here
Cause: You tried to tried to enable a
primary key constraint, but the
columns in the primary key either
contained NULL values or duplicates..

Answer 3

The maim reason of violation of primary ki is the atrrbute you making is nullable or you have some dupliactes in table for that id or attribute
create table client_master
(
client_no varchar2(6),
client_name varchar2(20),
city varchar2(25),
state varchar2(15),
pin number(6),
balance_due number(10,2));
for e.g,
after inserting values
0008 Mukul NYCT NYC 199560 2500
0006 Rukmini bombay maharastra 100001 0
0007 Krishna mathura up 900050 100000
0008 Mukul NYCT NYC 199560 2500
or your id is nullable
so just MODIFY THE ATTRIBUTE is and set to NOT NULL
also remove duplicates if any
DELETE client_master
WHERE rowid NOT IN
(SELECT MAX(rowid)
FROM client_master
GROUP BY client_no,client_name,city,state,pin,balance_due);
then you we will be able to add primary key to client _no

Answer 4

Are 2 primary keys identical?
This error is usually thrown when you try to create/enable a primary key on a table

Answer 5

I'm upvoting APC's answer, but since you seem to have some problems implementing it, could you just post the results of this query:
select my_id, count(*) from my_table group by my_id having count(*) >1
This will give us (and you) some idea of the problematic keys.