Select `CustomerLastName`,petshop_order.OrderNo, from customer,petshop_order,petshop_order_item,item And (customer.ssn=petshop_order.ssnAnd petshop_order.OrderNo = pet
:OObjectDatabaseTx db= OObjectDatabasePool.global().acquire("remote:localhost/petshopREGISTER THE CLASS ONLY ONCE AFTER THE DB IS OPEN/CREATED
db.getEntityManager().registerEntityClass("org.petshop.domain据我所见,对于每个REST请求,我都需要建立到数据库