1
List<Users> temp2;
temp2 = em.createQuery("SELECT u FROM Users u "
+ "NATURAL LEFT JOIN CourseMembers b "
+ "WHERE b.courseMembersPK.userID IS NULL").getResultList();
嗨!如果在另一个表中没有记录(CourseMembers
),我试图获取所有用户对象。你可以在JPA SQL javaEE中做自然左连接吗?
但我从我的EJB
收到此错误:
Caused by: Exception [EclipseLink-0] (Eclipse Persistence Services - 2.6.2.qualifier): org.eclipse.persistence.exceptions.JPQLException
Exception Description: Syntax error parsing [SELECT u FROM Users u NATURAL LEFT JOIN CourseMembers b WHERE b.courseMembersPK.userID IS NULL].
[21, 22] The FROM clause has 'Users u' and 'NATURAL LEFT JOIN CourseMembers b' that are not separated by a comma.
[30, 30] An identification variable must be provided for a range variable declaration.
我试图用逗号,但它给了我另一个错误。我该如何解决这个问题?
在此查询语言中,您必须使用对象结构。 – Jens
所以你不允许使用join? –
你可以使用连接。但不自然加入 – Jens