Question

开发环境参考：

Fedora FC18
Tomcat Server 7.0.39 (localhost config)
Eclipse Juno Release 2
Mysql-connecor-java Ver. 5.1.26 (jar)
Mysql-server Ver. 5.5.32 (jar)

以下选择语句失败，其中＆＃34;列＆＃39;深度＆＃39;找不到＆＃34;：

"select node.subEntityID, node.lft, node.rgt, (count(parent.subEntityID) - 1) as depth
 from ENTITY as node, ENTITY as parent
 where node.lft between parent.lft and parent.rgt
 group by node.subEntityID order by node.lft";

此select语句成功使用命令级mysql作为

use dbName;
select node.subEntityID, node.lft, node.rgt, (count(parent.subEntityID) - 1) as depth
  from ENTITY as node, ENTITY as parent
  where node.lft between parent.lft and parent.rgt
  group by node.subEntityID order by node.lft;

在MySQL Workbench ver中使用SQL查询时，select语句也会成功。 5.2.4.7。

相关的Java代码片段如下：

rs = stmt.executeQuery(typeEntityList);
// The depth alias does not print out in this for loop
for (int i=1; i<rs.getMetaData().getColumnCount()+1; i++) {
    System.out.println(rs.getMetaData().getColumnName(i));
    System.out.println(rs.getMetaData().getColumnLabel(i));
}
while (rs.next()) {
    // "depth" fails at the following statement
    System.out.println("depth: " + rs.getInt("depth"));
    String s = rs.getString("lft") + "  "
        + rs.getString("subEntityID") + "  "
        + rs.getString("rgt");
    System.out.println(s);
    entityList.add(s);
}

此外，我在Google搜索中发现MySQL的别名行为在最近的版本中发生了变化。建议的修复方法是将"?useOldAliasMetadataBehavior=true"附加到MySQL连接字符串以恢复到原始行为，但这不能解决问题。

这是堆栈跟踪：

java.sql.SQLException：列＆＃39;深度＆＃39;未找到。在com.mysql.jdbc.SQLError.createSQLException（SQLError.java:1078）在com.mysql.jdbc.SQLError.createSQLException（SQLError.java:989）在com.mysql.jdbc.SQLError.createSQLException（SQLError.java:975 ）在com.mysql.jdbc.ResultSetImpl.findColumn（ResultSetImpl.java:1167）的com.mysql.jdbc.SQLError.createSQLException（SQLError.java:920）com.mysql.jdbc.ResultSetImpl.getString（ResultSetImpl.java： 5733）在 EntityAssessmentEntityActions.EntityAssessmentEntityListAction.detailedEntityList（EntityAssessmentEntityListAction.java:184）在EntityAssessmentEntityActions.EntityAssessmentEntityListAction.execute（EntityAssessmentEntityListAction.java:69）在sun.reflect.NativeMethodAccessorImpl.invoke0（本机方法）在sun.reflect.NativeMethodAccessorImpl.invoke（NativeMethodAccessorImpl.java： 57）在sun.reflect.DelegatingMethodAccessorImpl.invoke（DelegatingMethodAccessorImpl.java:43）在java.lang.reflect.Method.invoke（Method.java:606）在com.opensymphony.xwork2.DefaultActionInvocation.invokeAction（DefaultActionInvocation.java:450 ）在com.opensymphony.xwork2.DefaultActionInvocation.invokeActionOnly（DefaultActionInvocation.java:289）在com.opensymphony.xwork2.DefaultActionInvocation.invoke（DefaultActionInvocation.java:252）在org.apache.struts2.interceptor.debugging.DebuggingInterceptor.intercept（ Debug.Interceptor.java:256）com.opensymphony.xwork2.DefaultActionInvocation.invoke（DefaultActionInvoc） ation.java:246）在com.opensymphony.xwork2.interceptor.DefaultWorkflowInterceptor.doIntercept（DefaultWorkflowInterceptor.java:176）在com.opensymphony.xwork2.interceptor.MethodFilterInterceptor.intercept（MethodFilterInterceptor.java:98）在com.opensymphony.xwork2位于org.apache.struts2.interceptor.validation.AnnotationValidationInterceptor.doIntercept（AnnotationValidationInterceptor.java:68）的com.opensymphony.xwork2.validator.ValidationInterceptor.doIntercept（ValidationInterceptor.java:265）中的.DefaultActionInvocation.invoke（DefaultActionInvocation.java:246）。）在com.opensymphony.xwork2.interceptor.MethodFilterInterceptor.intercept（MethodFilterInterceptor.java:98）在com.opensymphony.xwork2.DefaultActionInvocation.invoke（DefaultActionInvocation.java:246）在com.opensymphony.xwork2.interceptor.ConversionErrorInterceptor.intercept（ ConversionErrorInterceptor.java:138）com.opensymphony.xwork2.DefaultActionInvocation.invoke（DefaultActionInvocation.java:246）at com.opensymphony.xwork2.intercep tor.ParametersInterceptor.doIntercept（ParametersInterceptor.java:249）com.opensymphony.xwork2.interceptor.MethodFilterInterceptor.intercept（MethodFilterInterceptor.java:98）at com.opensymphony.xwork2.DefaultActionInvocation.invoke（DefaultActionInvocation.java:246）at com .opensymphony.xwork2.interceptor.ParametersInterceptor.doIntercept（ParametersInterceptor.java:249）在com.opensymphony.xwork2.interceptor.MethodFilterInterceptor.intercept（MethodFilterInterceptor.java:98）在com.opensymphony.xwork2.DefaultActionInvocation.invoke（DefaultActionInvocation.java ：246）在com.opensymphony.xwork2.interceptor.StaticParametersInterceptor.intercept（StaticParametersInterceptor.java:191）在com.opensymphony.xwork2.DefaultActionInvocation.invoke（DefaultActionInvocation.java:246）在org.apache.struts2.interceptor.MultiselectInterceptor。在org.apache.struts2.intercept上的com.opensymphony.xwork2.DefaultActionInvocation.invoke（DefaultActionInvocation.java:246）拦截（MultiselectInterceptor.java:73） or.CheckboxInterceptor.intercept（CheckboxInterceptor.java:91）在com.opensymphony.xwork2.DefaultActionInvocation.invoke（DefaultActionInvocation.java:246）在org.apache.struts2.interceptor.FileUploadInterceptor.intercept（FileUploadInterceptor.java:252）在COM .opensymphony.xwork2.DefaultActionInvocation.invoke（DefaultActionInvocation.java:246）com.opensymphony.xwork2.interceptor.ModelDrivenInterceptor.intercept（ModelDrivenInterceptor.java：100）at com.opensymphony.xwork2.DefaultActionInvocation.invoke（DefaultActionInvocation.java:246））com.opensymphony.xwork2.interceptor.ScopedModelDrivenInterceptor.intercept（ScopedModelDrivenInterceptor.java:141）at com.opensymphony.xwork2.DefaultActionInvocation.invoke（DefaultActionInvocation.java:246）at com.opensymphony.xwork2.interceptor.ChainingInterceptor.intercept（ ChainingInterceptor.java:145）com.opensymphony.xwork2.DefaultActionInvocation.invoke（DefaultActionInvocation.java:246）at com.opensymphony.xwork2.interceptor.PrepareInterceptor.d oIntercept（PrepareInterceptor.java:171）在com.opensymphony.xwork2.interceptor.MethodFilterInterceptor.intercept（MethodFilterInterceptor.java:98）在com.opensymphony.xwork2.DefaultActionInvocation.invoke（DefaultActionInvocation.java:246）在com.opensymphony.xwork2 .interceptor.I18nInterceptor.intercept（I18nInterceptor.java:176）在com.opensymphony.xwork2.DefaultActionInvocation.invoke（DefaultActionInvocation.java:246）在org.apache.struts2.interceptor.ServletConfigInterceptor.intercept（ServletConfigInterceptor.java:164）在com.opensymphony.xwork2.DefaultActionInvocation.invoke（DefaultActionInvocation.java:246）在com.opensymphony.xwork2.interceptor.AliasInterceptor.intercept（AliasInterceptor.java:193）在com.opensymphony.xwork2.DefaultActionInvocation.invoke（DefaultActionInvocation.java： 246）com.opensymphony.xwork2.interceptor.ExceptionMappingInterceptor.intercept（ExceptionMappingInterceptor.java:187）at com.opensymphony.xwork2.DefaultActionInvocation.invoke（DefaultActionInvocation.j） ava：246）org.apache.struts2.impl.StrutsActionProxy.execute（StrutsActionProxy.java:54）org.apache.struts2.dispatcher.Dispatcher.serviceAction（Dispatcher.java:546）org.apache.struts2.dispatcher .ng.ExecuteOperations.executeAction（ExecuteOperations.java:77）org.apache.struts2.dispatcher.ng.filter.StrutsPrepareAndExecuteFilter.doFilter（StrutsPrepareAndExecuteFilter.java:91）org.apache.catalina.core.ApplicationFilterChain.internalDoFilter（ApplicationFilterChain） .java：243）org.apache.catalina.core.ApplicationFilterChain.doFilter（ApplicationFilterChain.java:210）位于org.apache.catalina的org.apache.catalina.core.StandardWrapperValve.invoke（StandardWrapperValve.java:222）。 core.tandardContextValve.invoke（StandardContextValve.java:123）org.apache.catalina.authenticator.AuthenticatorBase.invoke（AuthenticatorBase.java:472）org.apache.catalina.core.StandardHostValve.invoke（StandardHostValve.java:171）在org.apache.catalina.valves.ErrorReportValve.invoke（ErrorReportValve.java:9 9）org.apache.catalina.valves.AccessLogValve.invoke（AccessLogValve.java:947）org.apache.catalina.core.StandardEngineValve.invoke（StandardEngineValve.java:118）org.apache.catalina.connector.CoyoteAdapter 。服务（CoyoteAdapter.java:408）在org.apache.coyote.http11.AbstractHttp11Processor.process（AbstractHttp11Processor.java:1009）在org.apache.coyote.AbstractProtocol $ AbstractConnectionHandler.process（AbstractProtocol.java:589）的组织。 apache.tomcat.util.net.JIoEndpoint $ SocketProcessor.run（JIoEndpoint.java:312）java.util.concurrent.ThreadPoolExecutor.runWorker（ThreadPoolExecutor.java:1145）at java.util.concurrent.ThreadPoolExecutor $ Worker.run（ ThreadPoolExecutor.java:615）在java.lang.Thread.run（Thread.java:724）

Answer 1

StackOverflow成员，我发现了这个问题，但是现在我因为把头发拉出来而秃顶。

在Eclipse Juno上，选择了Java源代码的“Organnize Imports”。“所以当我有一个未定义的变量时，我使用这个方便的选项来清理导入.Eclipse Juno导入了mysql连接器，”java .sql.connection“而不是”com.mysql.jdbc.connection“连接器。我更改了java源代码的导入，现在我很高兴继续使用这个servlet。但是在我出去找到一些之后就没有了。 Propecia或Rogaine或？... ... Roy W。

Answer 2

我在项目中遇到了类似的问题（我正在使用Eclipse Luna）。

我克服它的方法是将 MysqlDataSource 设置为 setUseOldAliasMetadataBehavior（true）;

带别名的MySQL select语句失败，找不到列

2 个答案: