一、查找备份表和原表不一样数据
java
select * from A where (select count(1) from A_BAK where A.ID=A_BAK.ID) = 0
二、在数据量比较大的表中新增有默认值的列速度较慢问题
使用 以下语句,在上亿数据的表中执行速度较慢
java
alter table TEST add col_a integer DEFAULT 0
可使用下面两种方式
java
alter table TEST add col_a integer DEFAULT 0 not null;
或者
java
alter table TEST add col_b integer;
alter table TEST modify col_b integer DEFAULT 0;
三、编译class文件java.lang.NoSuchFieldException: cacheList问题
在编译完class文件,替换war包里面对应class文件后,报Could not reload resource bundles java.lang.NoSuchFieldException: cacheList,找不到对应action,在网上查找资料,发现可能是JDK版本问题,原来使用JDK8 编译有问题,替换为JDK1.6编译,替换class文件后正常。
bash
com.opensymphony.xwork2.util.logging.commons.CommonsLogger error Could not reload resource bundles
java.lang.NoSuchFieldException: cacheList
at java.lang.Class.getDeclaredFieldImpl(Native Method)
at java.lang.Class.getDeclaredField(Class.java:575)
at com.opensymphony.xwork2.util.LocalizedTextUtil.clearMap(LocalizedTextUtil.java:835)
at com.opensymphony.xwork2.util.LocalizedTextUtil.reloadBundles(LocalizedTextUtil.java:794)
at com.opensymphony.xwork2.util.LocalizedTextUtil.reloadBundles(LocalizedTextUtil.java:780)
at com.opensymphony.xwork2.util.LocalizedTextUtil.findDefaultText(LocalizedTextUtil.java:205)
at com.opensymphony.xwork2.util.LocalizedTextUtil.findDefaultText(LocalizedTextUtil.java:227)
at org.apache.struts2.impl.StrutsActionProxy.getErrorMessage(StrutsActionProxy.java:70)
at com.opensymphony.xwork2.DefaultActionProxy.prepare(DefaultActionProxy.java:185)
at org.apache.struts2.impl.StrutsActionProxy.prepare(StrutsActionProxy.java:63)
at org.apache.struts2.impl.StrutsActionProxyFactory.createActionProxy(StrutsActionProxyFactory.java:39)
at com.opensymphony.xwork2.DefaultActionProxyFactory.createActionProxy(DefaultActionProxyFactory.java:58)
at org.apache.struts2.dispatcher.Dispatcher.serviceAction(Dispatcher.java:553)
at org.apache.struts2.dispatcher.ng.ExecuteOperations.executeAction(ExecuteOperations.java:77)
at org.apache.struts2.dispatcher.ng.filter.StrutsPrepareAndExecuteFilter.doFilter(StrutsPrepareAndExecuteFilter.java:99)
at com.ibm.ws.webcontainer.filter.FilterInstanceWrapper.doFilter(FilterInstanceWrapper.java:190)
at com.ibm.ws.webcontainer.filter.WebAppFilterChain.doFilter(WebAppFilterChain.java:125)
at org.springframework.web.filter.CharacterEncodingFilter.doFilterInternal(CharacterEncodingFilter.java:88)
at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:76)
at com.ibm.ws.webcontainer.filter.FilterInstanceWrapper.doFilter(FilterInstanceWrapper.java:190)
at com.ibm.ws.webcontainer.filter.WebAppFilterChain.doFilter(WebAppFilterChain.java:125)
at com.ibm.ws.webcontainer.filter.WebAppFilterChain._doFilter(WebAppFilterChain.java:80)
at com.ibm.ws.webcontainer.filter.WebAppFilterManager.doFilter(WebAppFilterManager.java:908)
at com.ibm.ws.webcontainer.filter.WebAppFilterManager.invokeFilters(WebAppFilterManager.java:997)
at com.ibm.ws.webcontainer.extension.DefaultExtensionProcessor.invokeFilters(DefaultExtensionProcessor.java:1079)
at com.ibm.ws.webcontainer.extension.DefaultExtensionProcessor.handleRequest(DefaultExtensionProcessor.java:999)
at com.ibm.ws.webcontainer.webapp.WebApp.handleRequest(WebApp.java:3954)
at com.ibm.ws.webcontainer.webapp.WebGroup.handleRequest(WebGroup.java:276)
at com.ibm.ws.webcontainer.WebContainer.handleRequest(WebContainer.java:945)
at com.ibm.ws.webcontainer.WSWebContainer.handleRequest(WSWebContainer.java:1592)
at com.ibm.ws.webcontainer.channel.WCChannelLink.ready(WCChannelLink.java:191)
at com.ibm.ws.http.channel.inbound.impl.HttpInboundLink.handleDiscrimination(HttpInboundLink.java:453)
at com.ibm.ws.http.channel.inbound.impl.HttpInboundLink.handleNewRequest(HttpInboundLink.java:515)
at com.ibm.ws.http.channel.inbound.impl.HttpInboundLink.processRequest(HttpInboundLink.java:306)
at com.ibm.ws.http.channel.inbound.impl.HttpInboundLink.ready(HttpInboundLink.java:277)
at com.ibm.ws.tcp.channel.impl.NewConnectionInitialReadCallback.sendToDiscriminators(NewConnectionInitialReadCallback.java:214)
at com.ibm.ws.tcp.channel.impl.NewConnectionInitialReadCallback.complete(NewConnectionInitialReadCallback.java:113)
at com.ibm.ws.tcp.channel.impl.AioReadCompletionListener.futureCompleted(AioReadCompletionListener.java:175)
at com.ibm.io.async.AbstractAsyncFuture.invokeCallback(AbstractAsyncFuture.java:217)
at com.ibm.io.async.AsyncChannelFuture$1.run(AsyncChannelFuture.java:205)
at com.ibm.ws.util.ThreadPool$Worker.run(ThreadPool.java:1656)
四、获取文件编码格式
java如何判断文件的编码格式_mob64ca12e36a1d的技术博客_51CTO博客