PostgreSQL Foreign Key ON DELETE Actions: CASCADE, SET NULL, RESTRICT Explained

A technical guide explains how to choose between ON DELETE CASCADE, SET NULL, and RESTRICT actions for foreign keys in PostgreSQL. The article advises selecting the action based on what should happen to child records when their parent record is deleted. SET NULL allows child rows to remain with a null link, but PostgreSQL may accept invalid definitions that only fail at deletion time if columns are NOT NULL. The guide recommends CASCADE when child rows become meaningless without the parent and RESTRICT/NO ACTION when child records must be preserved.