How to resolve the issue of MySQL being unable to add or update sub-rows?

If MySQL is unable to add or update child rows, here are some possible solutions:

1. Check the table structure to ensure it has enough columns to store sub-row data. If necessary columns are missing, they can be added by modifying the table structure.
2. Check foreign key constraints: Ensure that foreign key constraints are correctly set if the child rows depend on the parent row’s foreign key relationship. If foreign key constraints are not set, the issue can be resolved by modifying the table structure and adding appropriate foreign key constraints.
3. Check data integrity: Ensure that the parent row exists and meets the reference requirements of the child row. If the parent row does not exist or the reference value of the parent row does not match the reference requirements of the child row, the child row cannot be added or updated.
4. Check permissions: Ensure the MySQL user has enough permissions to perform the operation of adding or updating child rows. If there are insufficient permissions, the issue can be resolved by granting the appropriate permissions.
5. Check error logs: review the MySQL error log for additional details on why adding or updating child rows is not working. The error log usually offers detailed insights into what went wrong and can guide towards resolving the issue.

If the above methods still do not resolve the issue, you can provide more detailed information such as table structure, SQL query statements, and error messages to better understand the problem and provide a more accurate solution.