Hibernate查询给出java.lang.IllegalArgumentException：节点遍历不能为空 [英] Hibernate query giving java.lang.IllegalArgumentException: node to traverse cannot be null

问题描述

这个简单的查询

This simple query

session = com.jthink.songlayer.hibernate.HibernateUtil.getSession();
Query q = session.createQuery("recNo from SongChanges");

给这个堆栈跟踪

java.lang.IllegalArgumentException: node to traverse cannot be null!
    at org.hibernate.hql.internal.ast.util.NodeTraverser.traverseDepthFirst(NodeTraverser.java:63)
    at org.hibernate.hql.internal.ast.QueryTranslatorImpl.parse(QueryTranslatorImpl.java:272)
    at org.hibernate.hql.internal.ast.QueryTranslatorImpl.doCompile(QueryTranslatorImpl.java:180)
    at org.hibernate.hql.internal.ast.QueryTranslatorImpl.compile(QueryTranslatorImpl.java:136)
    at org.hibernate.engine.query.spi.HQLQueryPlan.<init>(HQLQueryPlan.java:101)
    at org.hibernate.engine.query.spi.HQLQueryPlan.<init>(HQLQueryPlan.java:80)
    at org.hibernate.engine.query.spi.QueryPlanCache.getHQLQueryPlan(QueryPlanCache.java:119)
    at org.hibernate.internal.AbstractSessionImpl.getHQLQueryPlan(AbstractSessionImpl.java:214)
    at org.hibernate.internal.AbstractSessionImpl.createQuery(AbstractSessionImpl.java:192)
    at org.hibernate.internal.SessionImpl.createQuery(SessionImpl.java:1537)

如果我这样做的话

if I do

session = com.jthink.songlayer.hibernate.HibernateUtil.getSession();
Query q = session.createQuery("from SongChanges");

我没有收到错误，但我只需要recNo

I dont get the error, but I only need the recNo

有什么想法？

Any ideas ?

推荐答案

您忘记了选择：

You forgot the select:

Query q = session.createQuery("select sc.recNo from SongChanges sc");

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