Plan how rows are removed

How to do it

Use ON DELETE CASCADE for rows that only exist as part of a parent, such as order lines. Use RESTRICT where a delete must be stopped. With a deleted_at column for soft deletes, every query must filter on it. Personal data must still be erased when the law asks.

Example

CREATE TABLE order_lines (
  order_id bigint NOT NULL REFERENCES orders (id) ON DELETE CASCADE,
  product_id bigint NOT NULL REFERENCES products (id) ON DELETE RESTRICT,
  quantity int NOT NULL CHECK (quantity > 0)
);

How to check

Delete a test parent row. Its owned rows disappear, protected references block the delete, and no orphan rows remain.