JPA降级:标准处理与JPQL处理
JPQL和标准API:JPA降级:标准处理与JPQL处理,jpa,jpql,criteria,Jpa,Jpql,Criteria,JPQL和标准API: SELECT o FROM Order o JOIN TREAT(o.product AS Book) b CriteriaQuery<Order> query = cb.createQuery(Order.class); Root<order> root = query.from(Order.class) Join product = root.join("product"); Join book = cb.treat(product, Boo
SELECT o
FROM Order o JOIN TREAT(o.product AS Book) b
CriteriaQuery<Order> query = cb.createQuery(Order.class);
Root<order> root = query.from(Order.class)
Join product = root.join("product");
Join book = cb.treat(product, Book.class);
query.select(root);
选择o
从订单o加入处理(o.产品作为书籍)b
CriteriaQuery=cb.createQuery(Order.class);
Root=query.from(Order.class)
Join product=root.Join(“产品”);
Join book=cb.treat(产品、书籍、类);
查询。选择(根);
他们是同一个问题吗?对于CriteriaAPI,cb.treat(…)创建一个新实例
属于联接(书本),但联接(书本)不用于查询
对于JPQL,根连接到处理过的连接(book)