ALTER TABLE sag_subscriptions
    ADD COLUMN IF NOT EXISTS billing_lead_months INTEGER NOT NULL DEFAULT 0,
    ADD COLUMN IF NOT EXISTS proration_basis VARCHAR(20) NOT NULL DEFAULT '30_day';

ALTER TABLE sag_subscriptions DROP CONSTRAINT IF EXISTS sag_subscriptions_billing_lead_months_check;
ALTER TABLE sag_subscriptions ADD CONSTRAINT sag_subscriptions_billing_lead_months_check
    CHECK (billing_lead_months BETWEEN 0 AND 24);

ALTER TABLE sag_subscriptions DROP CONSTRAINT IF EXISTS sag_subscriptions_proration_basis_check;
ALTER TABLE sag_subscriptions ADD CONSTRAINT sag_subscriptions_proration_basis_check
    CHECK (proration_basis IN ('30_day'));