It seems like you've provided a PHP warning related to a foreign key constraint violation in a database query.
The error message indicates that there is a problem with a foreign key constraint (fk_section_tab) in the section table.
The issue occurs when trying to add or update a record in the section table, specifically with the tab_id column.
The foreign key constraint references the tab table's tab_id column with ON DELETE CASCADE and ON UPDATE CASCADE actions. This means that changes to the referenced tab_id should cascade to the section table.
Possible Solutions:
Check Data Integrity: Ensure that the data in the section table aligns with the data in the tab table. Specifically, make sure that the tab_id values being inserted or updated in the section table exist in the tab table.
Check for Orphaned Records: If you have previously deleted records from the tab table without updating or deleting corresponding records in the section table, you may encounter this error. You should either remove or update these orphaned records in the section table.