View

• View就是一個虛擬表格
• Create view south as select * from service where area='南區'
• Create view money as select car.model as model , sum(car.price*sale.num) as total from car,sale where car.cid=sale.cid group by car.model
• 刪除是 drop view View_name
• View 不一定能夠 update delete