一、查找備份表和原表不一樣數(shù)據(jù)

select * from  A where (select count(1) from A_BAK where A.ID=A_BAK.ID) = 0 

二、在數(shù)據(jù)量比較大的表中新增有默認(rèn)值的列速度較慢問題

使用 以下語句，在上億數(shù)據(jù)的表中執(zhí)行速度較慢

alter table TEST add col_a integer DEFAULT 0

可使用下面兩種方式

alter table TEST add col_a integer DEFAULT 0 not null;

或者

alter table TEST add col_b integer；
alter table TEST modify col_b integer DEFAULT 0;

三、編譯class文件java.lang.NoSuchFieldException: cacheList問題

在編譯完class文件，替換war包里面對應(yīng)class文件后，報(bào)Could not reload resource bundles java.lang.NoSuchFieldException: cacheList，找不到對應(yīng)action，在網(wǎng)上查找資料，發(fā)現(xiàn)可能是JDK版本問題，原來使用JDK8 編譯有問題，替換為JDK1.6編譯，替換class文件后正常。

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、獲取文件編碼格式

java如何判斷文件的編碼格式_mob64ca12e36a1d的技術(shù)博客_51CTO博客

五、利用Oracle判斷表是否存在

利用Oracle判斷表是否存在的方法與技巧_筆記大全_設(shè)計(jì)學(xué)院文章來源地址http://www.zghlxwxcb.cn/news/detail-789028.html

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