NamedQueries使用什麼類型的查詢？

Question

我使用netbean的選項從數據庫創建實體類，我並不真正習慣於查詢的這個「方言」，我想了解更多關於它的語法。有人能告訴我這個查詢的「方言」或語法的名字是什麼？

@NamedQueries({ 
@NamedQuery(name = "Users.findAll", query = "SELECT u FROM Users u") 
, @NamedQuery(name = "Users.findByUserId", query = "SELECT u FROM Users u WHERE u.userId = :userId") 
, @NamedQuery(name = "Users.findByName", query = "SELECT u FROM Users u WHERE u.name= :name") 
, @NamedQuery(name = "Users.findBySurname", query = "SELECT u FROM Users u WHERE u.surname= :surname") 
, @NamedQuery(name = "Users.findByEmail", query = "SELECT u FROM Users u WHERE u.email = :email") 
, @NamedQuery(name = "Users.findByDateOfBirth", query = "SELECT u FROM Users u WHERE u.dateob= :dateob") 
, @NamedQuery(name = "Users.findByPassword", query = "SELECT u FROM Users u WHERE u.password= :password")}) 

Answer 1

它不是SQL，它是在JPA（Java持久性API）規範中定義的JPQL（Java持久性查詢語言）。

JPA的實現（例如Hibernate）會將它轉換爲正確的SQL方言中的SQL查詢，以查找它們正在訪問的數據源。