给一个表添加多个列，想指定after某一列，语法报错。
建议在添加多列场景下，支持：整体after或者单列after语句，事例如下：
alter table db.table ADD COLUMN (ad_id bigint key null comment '广告ID' after media_id, sponsor_id bigint key null comment '广告主ID' after media_id, sponsor_group_id bigint key null comment '广告主分组ID' after media_id ) ;
alter table db.table ADD COLUMN (ad_id bigint key null comment '广告ID' , sponsor_id bigint key null comment '广告主ID' , sponsor_group_id bigint key null comment '广告主分组ID' ) after media_id;
