Question

我正在尝试运行此命名查询，如果找到符合WHERE条件的记录，则返回1：

SELECT CASE WHEN EXISTS
(SELECT p
    FROM Books p
    WHERE bookNum = :bookNum
        AND author = :author
        AND bookID <> :bookID)
THEN 1
ELSE NULL
END

我使用EXISTS使其更快但我在 TOMCAT SERVER START 上出现此错误。

org.hibernate.hql.ast.QuerySyntaxException：意外的子树结束 [EXISTS时选择案例（SELECT p FROM com.userclasses.Books p WHERE bookNum =：bookNum AND author =：author AND bookID＆lt;＆gt; ：bookID）那么1 ELSE NULL END] at org.hibernate.hql.ast.QuerySyntaxException.convert（QuerySyntaxException.java:54）在 org.hibernate.hql.ast.QuerySyntaxException.convert（QuerySyntaxException.java:47）在 org.hibernate.hql.ast.ErrorCounter.throwQueryException（ErrorCounter.java:82）在 org.hibernate.hql.ast.QueryTranslatorImpl.analyze（QueryTranslatorImpl.java:261）在 org.hibernate.hql.ast.QueryTranslatorImpl.doCompile（QueryTranslatorImpl.java:185）在 org.hibernate.hql.ast.QueryTranslatorImpl.compile（QueryTranslatorImpl.java:136）在 org.hibernate.engine.query.HQLQueryPlan。（HQLQueryPlan.java:101）在 org.hibernate.engine.query.HQLQueryPlan。（HQLQueryPlan.java:80）在 org.hibernate.engine.query.QueryPlanCache.getHQLQueryPlan（QueryPlanCache.java:124）在 org.hibernate.impl.SessionFactoryImpl.checkNamedQueries（SessionFactoryImpl.java:549）在 org.hibernate.impl.SessionFactoryImpl。（SessionFactoryImpl.java:413）在 org.hibernate.cfg.Configuration.buildSessionFactory（Configuration.java:1872）在 org.hibernate.ejb.Ejb3Configuration.buildEntityManagerFactory（Ejb3Configuration.java:906）

我运行了下面的代码来获取hibernate版本，正如它在this link中所说的那样：它被修复了：

System.out.println(org.hibernate.Version.getVersionString());
System.out.println("Hibernate Version: "+ org.hibernate.annotations.common.Version.VERSION);

它在控制台中告诉我

3.6.4.Final
Hibernate Version: 3.2.0.Final

Answer 1

这解决了它

SELECT CASE WHEN EXISTS
(SELECT p
    FROM Books p
    WHERE bookNum = :bookNum
    AND author = :author
    AND bookID <> :bookID)
THEN 1
ELSE NULL
END FROM Books p

但是添加FROM Books p将不会提高性能，因为它现在将返回列表，而不是单个记录：（

使用SELECT CASE WHEN

1 个答案: