with temp as
(
    select region, avg([order]) as avgOrder
    from test
    group by region
)
select test.*
from test
inner join temp on temp.region = test.region
where test.[order] > temp.avgOrder

------解决方案--------------------

SQL code
SELECT * FROM orders AS o
WHERE `order` > (SELECT AVG(`order`) FROM orders
                 WHERE o.region=region)