SET FOREIGN_KEY_CHECKS=0;

ALTER TABLE `t_bill` ADD COLUMN IF NOT EXISTS `bill_set_explain` tinyint(1) NULL DEFAULT 0 AFTER `bill_merge_condition`;

ALTER TABLE `t_bill_order` ADD COLUMN IF NOT EXISTS `bill_explain` varchar(255) CHARACTER SET utf8 COLLATE utf8_general_ci NULL DEFAULT NULL AFTER `bill_order_supplement`;

SET FOREIGN_KEY_CHECKS=1;