mysql - 在不同数据库但同一个表中执行相同sql的简单方法

Question

我有八个数据库:order0,order2...order7,
他们都有表“订单”。
现在，我想要在所有八个数据库中执行像“select * from orders where order_id = 652454122”这样的sql。
我需要写这样的sql:

use order0
select * from orders where order_id = 652454122
use order1
select * from orders where order_id = 652454122
...
use order7
select * from orders where order_id = 652454122

需要复制七遍，太糟糕了!
有没有一些简单的方法，例如:

use order0/order1/order2... 
select * from orders where order_id = 652454122

Answer 1

创建联合所有 8 个表的 View ，例如:

CREATE VIEW vw_orders
AS
   SELECT *, 0 as DB FROM Order0..Orders
   UNION ALL
   SELECT *, 1 as DB FROM Order1..Orders
   UNION ALL
   ...
   SELECT *, 7 as DB FROM Order7..Orders

然后从中选择:

SELECT * FROM vw_orders WHERE order_id = 652454122