Question

这适用于Oracle，但我们已被告知切换到MySQL。更改驱动程序信息和其他相关设置以指向MySQL数据库后，我无法再执行我的命名查询。这是实体中定义的最简单的一个：

@NamedQuery（name =“get_capability”，query =“从Capability cb中选择cb，其中cb.financial_Id =：fiId”）

然后我有代码来执行查询，如下所示：

query = em.createNamedQuery（“get_capability”）;

。   。

query.setParameter（“fiId”，fiId）;

query.setMaxResults（1）;

cabability =（Capability）query.getSingleResult（）;

最后一行抛出异常：

2013-04-24 10：46：00,677 WARN [org.hibernate.util.JDBCExceptionReporter]（http-127.0.0.1-8080-1）SQL错误：1248，SQLState：42000

2013-04-24 10：46：00,677 ERROR [org.hibernate.util.JDBCExceptionReporter]（http-127.0.0.1-8080-1）每个派生表必须有自己的别名

生成的SQL记录在日志文件中，如下所示：

/* named HQL query get_capability */ select
    * 
from
    ( select
        capability0_.FINANCIAL_ID as FINANCIAL1_272_,
        capability0_.ACTIVE_CONNECTIONS as ACTIVE2_272_,
        capability0_.ALLOWED_CONNECTIONS as ALLOWED3_272_,
        capability0_.COMPLETE_DETAILS as COMPLETE4_272_,
        capability0_.FI_NAME as FI5_272_,
        capability0_.MESSAGE_FORMAT as MESSAGE6_272_,
        capability0_.PROVIDER_ID as PROVIDER7_272_,
        capability0_.STATUS as STATUS272_,
        capability0_.SUPPORTS_ACCOUNTS as SUPPORTS9_272_,
        capability0_.SUPPORTS_CUSTOMER as SUPPORTS10_272_,
        capability0_.SUPPORTS_IMAGE as SUPPORTS11_272_,
        capability0_.SUPPORTS_STATEMENTS as SUPPORTS12_272_,
        capability0_.SUPPORTS_TRANSACTIONS as SUPPORTS13_272_,
        capability0_.SUPPORTS_TRANSFER as SUPPORTS14_272_ 
    from
        INSTITUTION capability0_ 
    where
        capability0_.FINANCIAL_ID=? ) 
where
    rownum <= ?

我已经阅读了这个错误意味着什么，每个派生表都需要一个别名，我可以通过添加别名来编辑派生SQL以使其工作。我的问题是这个。由于这是派生查询（SQL），如何告诉hibernate添加别名，或告诉MySQL不要求它？

Hibernate部分配置：

<property name="hibernate.dialect" value="org.hibernate.dialect.MySQLDialect" />   
<property name="hibernate.connection.driver_class" value="com.mysql.jdbc.Driver"/> 
<property name="hibernate.showSql" value="true" /> 
<property name="hibernate.format_sql" value="true"/> 
<property name="hibernate.use_sql_comments" value="true"/>

Answer 1

由于ROWNUM是MySQL不支持的Oracle关键字（例如，请参阅this question），我认为Hibernate在构建查询时仍然以Oracle为目标。

确认您已更改为相应的Hibernate方言。

（为子孙后代添加的答案）

Answer 2

FROM中的子查询是＆＃34;派生表＆＃34;，您必须命名该派生表。

这样的事情应该有效

select
    RES.field1, RES.field2 
from
    ( select
        capability0_.FINANCIAL_ID as FINANCIAL1_272_,
        capability0_.ACTIVE_CONNECTIONS as ACTIVE2_272_,
        capability0_.ALLOWED_CONNECTIONS as ALLOWED3_272_,
        capability0_.COMPLETE_DETAILS as COMPLETE4_272_,
        capability0_.FI_NAME as FI5_272_,
        capability0_.MESSAGE_FORMAT as MESSAGE6_272_,
        capability0_.PROVIDER_ID as PROVIDER7_272_,
        capability0_.STATUS as STATUS272_,
        capability0_.SUPPORTS_ACCOUNTS as SUPPORTS9_272_,
        capability0_.SUPPORTS_CUSTOMER as SUPPORTS10_272_,
        capability0_.SUPPORTS_IMAGE as SUPPORTS11_272_,
        capability0_.SUPPORTS_STATEMENTS as SUPPORTS12_272_,
        capability0_.SUPPORTS_TRANSACTIONS as SUPPORTS13_272_,
        capability0_.SUPPORTS_TRANSFER as SUPPORTS14_272_ 
    from
        INSTITUTION capability0_ 
    where
        capability0_.FINANCIAL_ID=? ) **RES**
where
    rownum <= ?

从Oracle Db切换到MySQL。命名查询不再有效

2 个答案: