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ORA-00001: unique constraint (string.string) violated

The ORA-00001: unique constraint (string.string) violated error comes when you try to update or insert a record in a table(Oracle Database) that creates a duplicate on the columns which are defined as unique.

As per Oracle error message guide,

ORA-00001: unique constraint (string.string) violatedCause: An UPDATE or INSERT statement attempted to insert a duplicate key. For Trusted Oracle configured in DBMS MAC mode, you may see this message if a duplicate entry exists at a different level.

Action: Either remove the unique restriction or do not insert the key.

Let’s reproduce ORA-00001

Let’s say you have a table employee where employee_id is either a primary key or you have defined a unique constraint on it.

CREATE TABLE employee (
    employe_id   NUMBER PRIMARY KEY,
    name         VARCHAR2(100)

Note:- Oracle creates a unique constraint on the column defined as a primary key.

Insert data in this table

INSERT INTO employee VALUES (100,'Steve');
INSERT INTO employee VALUES (101, 'Thomas');

Now insert records with a duplicate value

SQL> INSERT INTO employee VALUES (100,'John');
INSERT INTO employee VALUES (100,'John')
ERROR at line 1:
ORA-00001: unique constraint (APPS.SYS_C001228683) violated

Now you already have an employee steve with employee_id =100 and there is an insert or update on this table which tries to create another record with employee_id =100. This violates the unique constraint on the employee_id columns and you get,

ERROR at line 1:

ORA-00001: unique constraint (APPS.SYS_C001228683) violated


Just drop the unique constraint on columns to resolve the ORA-00001: unique constraint error in Oracle Database.


In summary, ORA-00001 is a common Oracle error that is encountered when there is a violation of a unique or primary key constraint. It underscores the critical role of data integrity mechanisms, such as unique and primary key constraints, in maintaining the consistency and reliability of database content.

Addressing this error requires reviewing and correcting the data and ensuring that applications and scripts handling data operations are well-designed to uphold data integrity rules. Developing sophisticated error handling and data validation mechanisms is fundamental to mitigating the occurrence of this error, enhancing the overall database management experience.