1.
 MERGE tbl AS target
USING tb2  AS source 
ON (target.id = source.id)

WHEN MATCHED and source.price >450 
then  
UPDATE SET TARGET.price = SOURCE.price, 
TARGET.group = SOURCE.group 

 2.
 update tb1 
set 
tb1.price=tb2.price, 
tb1.group=tb2.group from tb2 
left join tb1 on tb1.id =tb2.id 
where tb1.id =tb2.id 
and tb1.price>450