ALTER TABLE `zh_material_stage_bills` ADD `expr` VARCHAR(1000) NULL DEFAULT NULL COMMENT '表达式' AFTER `quantity`;
-- 同步旧数据
UPDATE `zh_material_stage_bills` a, `zh_material_bills` b SET a.`expr`= b.`expr` WHERE a.`mb_id` = b.`id`;

UPDATE `zh_material_bills` a, `zh_material` b SET a.`expr`= null WHERE a.`mid` = b.`id` AND t_type = 2 AND b.`is_stage_self` = 1;
