Enforce data integrity at the schema level with NOT NULL, UNIQUE, CHECK, and FK constraints.
Without DB-level constraints, invalid or null data slips in and every consumer must defensively re-validate.
BeforeMerge scans your pull requests against this rule and dozens more. Get actionable feedback before code ships.
Application code is not the only writer — migrations, scripts, and other services touch the table too. Database constraints are the single source of truth that no path can bypass, catching bad data at write time instead of corrupting reads everywhere.
-- Bad: nothing stops nulls, dupes, or negative prices
CREATE TABLE product (id uuid, email text, price numeric);-- Good: integrity enforced by the schema
CREATE TABLE product (
id uuid PRIMARY KEY,
email text NOT NULL UNIQUE,
price numeric NOT NULL CHECK (price >= 0)
);