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Description

Error 23000, 'integrity constraint violation', indicates that an attempted database operation (such as INSERT, UPDATE, or DELETE) has violated one of the defined integrity rules of the database. This typically occurs when data does not conform to unique, referential, or check constraints, preventing the database from maintaining consistency and validity.

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Error Message

integrity constraint violation

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Known Causes

4 known causes

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Foreign Key Breach

An operation attempted to reference a non-existent value in a related table, violating a foreign key constraint (referential integrity).

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Duplicate Key Entry

A unique constraint was violated by trying to add data that duplicates an existing unique value in a column or set of columns.

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Check Constraint Failure

Data failed to meet the conditions specified by a CHECK constraint, which enforces domain integrity on column values.

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Missing Required Value

An attempt was made to insert a NULL value into a column that has a NOT NULL constraint, requiring a specific value.

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Solutions

4 solutions available

1. Identify and Correct Violating Data medium

Locate the specific row(s) causing the constraint violation and modify them.

1

Examine the PostgreSQL error message carefully. It usually provides clues about which constraint was violated and often indicates the table and sometimes even the offending data.

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2

If the error message isn't detailed enough, you can try to identify the violating data by querying the table. For example, if you suspect a unique constraint violation, you might look for duplicate values.

SELECT column_name, COUNT(*) FROM your_table GROUP BY column_name HAVING COUNT(*) > 1;

3

Once the violating data is identified, either update the problematic values to be unique/valid or delete the offending row(s).

UPDATE your_table SET column_name = 'new_unique_value' WHERE id = offending_row_id;
DELETE FROM your_table WHERE id = offending_row_id;

4

Re-attempt the operation that caused the error.

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2. Temporarily Disable and Re-enable Constraints easy

Disable a constraint to allow data loading, then re-enable it after data is imported.

1

Identify the constraint causing the issue. You can find constraint names in the PostgreSQL system catalogs or often in the error message itself.

SELECT conname FROM pg_constraint WHERE conrelid = 'your_table'::regclass AND contype = 'u'; -- For unique constraints
SELECT conname FROM pg_constraint WHERE conrelid = 'your_table'::regclass AND contype = 'f'; -- For foreign key constraints

2

Temporarily disable the constraint. This is often done within a transaction to ensure atomicity.

BEGIN;
ALTER TABLE your_table DISABLE TRIGGER ALL; -- Or specific trigger if known
-- Perform your data loading/modification operations here
-- ...
ALTER TABLE your_table ENABLE TRIGGER ALL; -- Or specific trigger
COMMIT;

3

If disabling triggers is not sufficient or the constraint is not trigger-based (e.g., a CHECK constraint), you might need to drop and re-create the constraint. This is more involved and requires careful planning.

ALTER TABLE your_table DROP CONSTRAINT constraint_name;
-- Perform your data loading/modification operations here
-- ...
ALTER TABLE your_table ADD CONSTRAINT constraint_name CHECK (your_condition); -- Or other constraint type

4

After the data operation is complete, re-enable the constraint. If you dropped and re-created it, ensure the re-creation syntax is correct.

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3. Review and Adjust Application Logic medium

Modify the application code to prevent data that violates constraints from being inserted or updated.

1

Analyze the application code that performs database operations. Look for places where data is inserted or updated into tables with constraints.

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2

Implement validation logic in your application before sending data to the database. This can include checking for unique values, data types, referential integrity, etc.

javascript
// Example in Node.js with a hypothetical ORM
async function createUser(userData) {
  const existingUser = await db.query('SELECT 1 FROM users WHERE email = $1', [userData.email]);
  if (existingUser.rows.length > 0) {
    throw new Error('Email address already in use.');
  }
  await db.query('INSERT INTO users (name, email) VALUES ($1, $2)', [userData.name, userData.email]);
}

3

Handle potential constraint violations gracefully in your application's error handling. Instead of letting the raw database error propagate, catch it and provide user-friendly feedback.

python
try:
    cursor.execute("INSERT INTO products (name, price) VALUES (%s, %s)", ('Widget', -10.0))
except psycopg2.IntegrityError as e:
    print(f"Data integrity error: {e}")
    # Provide user feedback or log the error

4

Test your application thoroughly after making changes to ensure the validation and error handling work as expected.

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4. Modify or Drop Constraint advanced

Alter the constraint definition or remove it if it's no longer needed or incorrectly defined.

1

Carefully evaluate the purpose and necessity of the constraint. Is it still relevant to your data model and business rules?

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2

If the constraint is too restrictive or incorrect, you can modify it. For example, changing a unique constraint to allow nulls or adjusting a check constraint's condition.

ALTER TABLE your_table ALTER COLUMN column_name DROP NOT NULL;
ALTER TABLE your_table ALTER COLUMN column_name DROP EXPRESSION;
ALTER TABLE your_table ADD CONSTRAINT constraint_name CHECK (new_condition);

3

If the constraint is no longer required, you can drop it. This should be done with extreme caution as it removes data integrity guarantees.

ALTER TABLE your_table DROP CONSTRAINT constraint_name;

4

After modifying or dropping a constraint, ensure you test your application and data operations to confirm the desired behavior and that no new issues arise.

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Related Errors

5 related errors

PostgreSQL Error 23000: Data Integrity Violation