-- 合同表新增6个字段
ALTER TABLE asset_contract
  ADD COLUMN hydrogen_bearer VARCHAR(20) COMMENT '氢费承担方',
  ADD COLUMN hydrogen_payment_method VARCHAR(20) COMMENT '氢气付款方式',
  ADD COLUMN hydrogen_prepay DECIMAL(12,2) COMMENT '氢气预付款',
  ADD COLUMN hydrogen_return_price DECIMAL(12,2) COMMENT '退还车氢气单价',
  ADD COLUMN billing_method VARCHAR(50) COMMENT '账单计算方式',
  ADD COLUMN main_vehicle_type VARCHAR(50) COMMENT '主车型';