SQL SERVER – Difference Between Union vs. Union All – Optimal Performance Comparison
摘要：More than a year ago I had written articleSQL SERVER – Union vs. Union All – Which is better for performance?I have got many request to update this article. It is not fair to update already written article so I am rewriting it again with additional information.UNIONThe UNION command is used to selec
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IE6下雪碧图多次请求fix方法
摘要：在ie6下发现雪碧图有同一图片多次请求的bug，请在head中增加如下代码以解决问题(最好不要放在底部，否则效果不能保证). <!--[if IE 6]> <script type="text/javascript">try { document.execCommand('BackgroundImageCache', false, true); } catch(e) {}</script> <![endif]-->
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