The error means a referenced index or primary/foreign key name is missing from the target table.
MySQL Error 1176: ER_KEY_DOES_NOT_EXITS occurs when a query refers to an index or constraint that is not defined on the specified table. Rename the key in the statement or create the missing index to resolve the issue.
Key '%s' doesn't exist in table '%s'
The server raises code 1176 with message "Key '%s' doesn't exist in table '%s'" when a statement references an index or constraint name that the table metadata cannot find.
The error commonly appears during ALTER TABLE, DROP INDEX, DROP FOREIGN KEY, or EXPLAIN statements that expect an index name to be present.
Leaving the issue unresolved blocks schema migrations, hampers query optimization, and may hide deeper metadata drift between your codebase and database.
Mismatch between the key name in the SQL statement and the actual index name, often due to typos or case sensitivity.
Key was previously dropped by another migration or manual intervention, so later scripts cannot find it.
Dump and restore operations renamed or truncated long key names exceeding MySQL limits.
Using a different schema or connection than expected, leading to table references that do not contain the key.
Verify the exact index or constraint names with SHOW INDEX FROM table_name and SHOW CREATE TABLE table_name.
Correct the statement to match the existing key name or create the missing index before altering or dropping it.
Ensure deployment order of migrations so that a DROP or ALTER only runs after the key has been created.
Altering a column requires dropping a foreign key first - create the foreign key if it never existed or adjust the name.
Rolling back a migration tries to drop the same index twice - add IF EXISTS or guard the rollback with existence checks.
Adopt consistent naming conventions and store them in version control.
Use automated schema diff tools that verify key presence before executing migrations.
Leverage Galaxy SQL editor collections to share endorsed migration scripts, reducing typo risk.
Error 1005 (HY000) - Can't create table: occurs when referenced key missing during foreign key creation; ensure parent index exists.
Error 1064 - SQL syntax error: validate query syntax, especially around ALTER or DROP clauses.
Error 1826 - Duplicate foreign key name: rename new constraint to avoid collision.
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Run SHOW INDEX FROM table_name or review SHOW CREATE TABLE table_name for a full list of indexes and key names.
The server stores key names in the data dictionary as given, but comparisons are case insensitive on Windows and macOS and case sensitive on many Linux setups because of file-system behavior.
Yes. MySQL 8.0 supports ALTER TABLE ... DROP INDEX IF EXISTS key_name to prevent errors in repeatable scripts.
Galaxy's AI copilot auto-completes correct index names from live schema metadata, and Collections let teams endorse migration scripts, reducing typo-related ER_KEY_DOES_NOT_EXITS issues.
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