ALTER TABLE  "member_benefits"
   ADD COLUMN "limit_num" int4 DEFAULT 0,
  ADD COLUMN "limit_time_type" varchar(32),
  ADD COLUMN "limit_time_value" int4;

COMMENT ON COLUMN "member_benefits"."limit_num" IS '每日限购';

COMMENT ON COLUMN "member_benefits"."limit_time_type" IS '限购时间类型';

COMMENT ON COLUMN "member_benefits"."limit_time_value" IS '限购时间值';