ppanel-web/migrations/mysql/02108_user_referral.sql

ALTER TABLE `user`
    ADD COLUMN `referral_percentage` TINYINT UNSIGNED NOT NULL DEFAULT 0
      COMMENT 'Referral Percentage'
      AFTER `commission`,
    ADD COLUMN `only_first_purchase` TINYINT(1) NOT NULL DEFAULT 1
      COMMENT 'Only First Purchase'
      AFTER `referral_percentage`;