text: --liquibase formatted sql
  
  --changeset uk.gov.pay:alter_table-service_gateway_accounts-add-constraint-back
  ALTER TABLE service_gateway_accounts ADD CONSTRAINT service_gateway_accounts_gateway_account_id_key UNIQUE (gateway_account_id);
  
  --rollback ALTER TABLE service_gateway_accounts DROP CONSTRAINT service_gateway_accounts_gateway_account_id_key;
  