How to resolve ORA-02437 Error Message in Oracle database

Learn the purpose and how to get to the bottom of the ORA-02437 error message in Oracle.

Description

When you encounter an ORA-02437 error, the following error message will appear:

ORA-02437: can’t validate – principal key violated

Cause

You tried to allow a main key constraint, but the columns in the fundamental key both contained NULL values or duplicates.

Resolution

The option(s) to resolve this Oracle error are:

Option #1

This error happens when you try to allow a major key when there is information in the table, and the columns that make up the foremost key incorporate both NULL values.

For example, if you created the following table:

CREATE TABLE supplier
( supplier_id numeric(10),
  supplier_name varchar2(50),
  CONSTRAINT supplier_pk PRIMARY KEY (supplier_id)
);

And then the primary key was disabled as follows:

ALTER TABLE supplier;
disable CONSTRAINT supplier_pk;

Then statistics was inserted into the provider table with a NULL price for the supplier_id as follows:

INSERT INTO supplier
( supplier_id, supplier_name )
VALUES
(NULL, 'IBM');

And then you tried to enable the primary key:

ALTER TABLE supplier
enable CONSTRAINT supplier_pk;

You would receive the following error message:

You may want to correct this error by way of casting off the document from the supplier table where the supplier_id column carries a NULL fee or you could assign a NOT NULL value to the supplier_id column.

Option #2

This error occurs when you attempt to enable a essential key when there is data in the table, and the columns that make up the predominant key include duplicates.

For example, if you created the following table:

CREATE TABLE supplier
( supplier_id numeric(10),
  supplier_name varchar2(50),
  CONSTRAINT supplier_pk PRIMARY KEY (supplier_id)
);

And then the primary key was disabled as follows:

ALTER TABLE supplier
 DISABLE CONSTRAINT supplier_pk;

Then facts was once inserted into the provider table to create duplicates in the supplier_id discipline as follows:

INSERT INTO supplier
( supplier_id, supplier_name )
VALUES
(1, 'IBM');

INSERT INTO supplier
( supplier_id, supplier_name )
VALUES
(1, 'Microsoft');

And then you tried to enable the primary key:

ALTER TABLE supplier
 ENABLE CONSTRAINT supplier_pk;

You would receive the following error message:

You could right this error by way of getting rid of the reproduction information from the provider table.