主题：迅速找到两个表之间的订单差异

select 订单号  from {A表} as a  where not exists(select 订单号 from {B表} as b where a.订单号=b.订单号) union select 订单号  from {B表} as a  where not exists(select 订单号 from {A表} as b where a.订单号=b.订单号)