add service

migrations/00008_add_balance_check_constraint.sql

@@ -0,0 +1,10 @@
+-- +goose Up
+ALTER TABLE users ADD CONSTRAINT balance_non_negative CHECK (balance >= 0);
+
+ALTER TABLE invite_codes ADD CONSTRAINT used_count_non_negative CHECK (used_count >= 0);
+ALTER TABLE invite_codes ADD CONSTRAINT used_count_within_limit CHECK (used_count <= can_be_used_count);
+
+-- +goose Down
+ALTER TABLE users DROP CONSTRAINT IF EXISTS balance_non_negative;
+ALTER TABLE invite_codes DROP CONSTRAINT IF EXISTS used_count_non_negative;
+ALTER TABLE invite_codes DROP CONSTRAINT IF EXISTS used_count_within_limit;