<p>The error appears when inserting or updating a child row would create a duplicate key value already present in the referenced parent table.</p>
<p>MySQL Error 1761: ER_FOREIGN_DUPLICATE_KEY_WITH_CHILD_INFO triggers when a child insert or update duplicates a key that already exists in the parent table. Remove or merge the conflicting parent or child rows, then retry the statement to resolve the issue.</p>
Foreign key constraint for table '%s', record '%s' would
MySQL raises this error when an INSERT or UPDATE on a child table violates a UNIQUE key in the referenced parent table. The engine detects that the operation would create two parent rows with the same primary or unique key, breaking referential integrity.
The SQL state 23000 flags an integrity constraint violation. Because foreign keys guarantee 1-to-1 or 1-to-many relationships, MySQL refuses any change that produces duplicate parent values, protecting data consistency.
Most cases involve duplicate values inside the parent table itself or concurrent transactions inserting identical parent keys. When the child row points to that key, InnoDB detects the impending duplicate and aborts the statement.
Bulk migrations, poorly written upserts, and missing unique indexes on parent tables also create scenarios where two parent rows share the same referenced column, producing the duplicate-key conflict.
First, locate conflicting parent rows with SELECT queries on the referenced columns. Remove extras or merge them into a single consistent record. Then correct child rows to reference the surviving parent ID before re-enabling the foreign key constraint.
If concurrency is the culprit, wrap inserts in transactions with proper isolation or use INSERT IGNORE / ON DUPLICATE KEY UPDATE to steer duplicates into an UPDATE instead of a new row.
During data imports, disable foreign key checks only long enough to load data, then run de-duplication queries and re-enable constraints. This sequence avoids partial loads that later break applications.
When sharding or archiving, ensure each shard maintains unique parent keys. Cross-shard merges should run a de-duplication script before attaching the shard to production.
Always place a UNIQUE or PRIMARY KEY on columns referenced by foreign keys. This guarantees single-row parent targets and lets MySQL catch duplicates early.
Automate integrity tests in CI pipelines. Galaxy users can run pre-merge scripts that verify no duplicate parent keys exist and block deployments that would introduce them.
Error 1452 (ER_NO_REFERENCED_ROW) occurs when the parent row is missing entirely, while Error 1451 (ER_ROW_IS_REFERENCED) blocks deletion of a parent row that still has children. Both are resolved by inserting the missing parent or updating/deleting child references respectively.
Two or more rows in the parent table share the same primary or unique key that the child table references.
Simultaneous transactions insert identical parent keys, creating a race condition that surfaces when a child row tries to reference them.
Without a UNIQUE constraint, the parent table silently accepts duplicates until the foreign key interaction exposes the conflict.
Bulk loads or ETL jobs insert duplicate parent records or reorder statements in a way that breaks referential integrity.
Triggered when the referenced parent row is missing entirely.
Occurs when attempting to delete a parent row that still has child references.
A general duplicate key error not necessarily tied to foreign keys but often seen alongside constraint issues.
Run a GROUP BY query on the parent key and filter with HAVING COUNT(> 1). This instantly shows offending values.
SET FOREIGN_KEY_CHECKS = 0 allows loading data, but always deduplicate and re-enable checks afterward to avoid hidden corruption.
No. MySQL refuses to create the index if duplicates exist. Clean the data first, then add the constraint.
Galaxy’s AI copilot surfaces missing UNIQUE constraints during query reviews and runs automated integrity tests before merging schema changes.
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