SQL为触发器删除引发错误

Question

我对我尝试删除的语句有疑问。当我从保留表中删除一个元组时，它会提示我一个错误，说明所选的3行无法修改。

 Create TRIGGER [ReserveTrig] 
 ON [Reserve]
 After Delete
 As

 Declare @confirm_ID int
 Declare @veh_no varchar(50)

 SELECT @DEL = COUNT(*) FROM DELETED

 Select @veh_no = plateNo, @confirm_ID = confirmID
 from deleted

 Update Vehicles set [status] = 'Available' where plateNo = @veh_no

 Delete from Reservation where confirmID = @confirm_ID

我们将非常感谢您的协助。