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mysql使用别名有啥好处没

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mysql使用别名有啥好处没

如图：使用别名真的能节省资源吗？
Image 898.png


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主要功能是重命名，使得输出结果更加可读。至于你的例子中是否有提高性能，我没有仔细去查sql规范不太清楚，但是我觉得线代sql引擎肯定会做优化，不至于avg会做两次。后面的avg看似要做运算但是我猜测只是对前面的avg结果的一个引用而已


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