The ER_DUP_ENTRY error signals that a UNIQUE or PRIMARY KEY index already contains the value you are trying to insert or update.
MySQL Error 1062 ER_DUP_ENTRY occurs when an INSERT or UPDATE attempts to write a value that already exists in a UNIQUE or PRIMARY KEY column. Eliminate or modify the duplicate value, or adjust the index definition, to resolve the conflict.
Duplicate entry '%s' for key %d
Error 1062 fires when MySQL detects a duplicate value for a column or set of columns covered by a UNIQUE or PRIMARY KEY constraint. The server blocks the statement and returns the message “Duplicate entry '%s' for key %d.”
This runtime error protects data integrity by ensuring that each unique index stores distinct values.
Ignoring it can lead to inconsistent records and unreliable query results.
Duplicate primary-key values trigger the error most often.
Attempting to insert a row whose id already exists in the table immediately fails.
Updates that change a non-unique value to one that is already present also raise the error, even when the original row passed validation.
First identify the conflicting value by reading the error text or running a SELECT query. Remove or change the duplicate row, then re-run the statement.
If the value should not be unique, drop or alter the index.
If duplicates are legitimate only in rare cases, consider a composite UNIQUE index that includes more columns.
Bulk imports often fail because source data contains repeated keys. Load the data into a staging table, de-duplicate, then move clean rows into production tables.
Parallel workers inserting sequential ids without coordination can collide.
Use AUTO_INCREMENT with an adequate allocation block or switch to UUIDs.
Always review your UNIQUE indexes to be sure they match business rules. Test inserts with representative data before deploying schema changes.
Use Galaxy’s AI copilot to scan scripts for potential key conflicts and to preview inserts in a sandbox connection before they reach production.
Error 1136 (ER_WRONG_VALUE_COUNT_ON_ROW) signals mismatched column counts during insert.
Unlike 1062, it concerns column alignment, not uniqueness.
Error 1452 (ER_NO_REFERENCED_ROW) indicates a missing parent row required by a FOREIGN KEY. Resolve it by inserting the parent or disabling the constraint temporarily.
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Ignoring the error is risky because it compromises data integrity. Always address the duplicate or modify the index intentionally.
Yes, AUTO_INCREMENT guarantees unique numeric values, but manual inserts that specify the id can still collide.
Galaxy’s AI copilot previews inserts, flags potential key clashes, and lets teams run queries in a shared workspace that surfaces constraint violations early.
Using SET unique_checks=0 is safe only during controlled bulk loads into an empty table, followed by careful validation.
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