Error
Error Code:
3104
MySQL Error 3104: FK on Generated Column
Description
This error occurs when you attempt to define a foreign key constraint on a generated column in MySQL, and simultaneously include an `ON DELETE` or `ON UPDATE` clause. MySQL restricts the use of these clauses for foreign keys that reference generated columns. It typically arises during `CREATE TABLE` or `ALTER TABLE` operations.
Error Message
Cannot define foreign key with %s clause on a generated column.
Known Causes
3 known causesDirect FK Constraint
Attempting to define a foreign key on a generated column with `ON DELETE` or `ON UPDATE` clauses directly within a `CREATE TABLE` or `ALTER TABLE` statement.
Misidentified Column Type
Unintentionally applying a foreign key with action clauses to a column that is a generated column, due to an oversight in schema understanding or design.
Tool-Generated DDL Error
Database management tools or ORMs generating incorrect DDL statements that include forbidden foreign key clauses on generated columns.
Solutions
Coming SoonDetailed step-by-step solutions for this error are being prepared. In the meantime, try these general troubleshooting tips:
General Troubleshooting Tips
- Check the error message carefully for specific details
- Review recent changes that might have caused the error
- Search for the exact error code in the official documentation
- Check log files for additional context
- Try restarting the application or service