psql "$DATABASE_URL" -v ON_ERROR_STOP=1 <<'SQL' SET lock_timeout = '30s'; ALTER TABLE users ADD CONSTRAINT chk_email_format CHECK (email ~* '^[A-Za-z0-9._%+-]+@[A-Za-z0-9.-]+\.[A-Za-z]{2,}$'); SELECT conname, convalidated FROM pg_constraint WHERE conname = 'chk_email_format'; SQL