论文摘要 高分求人翻译

来源：百度知道 编辑：UC知道 时间：2024/05/15 06:52:58
对于数据量庞大的数据库而言，劣质SQL语句和优质SQL语句之间的查询速度差别可以达到几十甚至上百倍。
在实际应用中，一个查询系统不是简单地能实现其功能就行，对于一些需要实时响应的查询系统而言，
如果因为没有高质量的SQL语句造成性能低下，即使能实现其功能也无意义。
SQL查询优化的实质就是在结果正确的前提下。优化器根据定义的索引来提高查找效率，
使用优化的SELECT语句，尽量避免全表扫描的发生，提高查询速度，提高工作效率。
本文就是从索引的创建和SELECT语句的优化出发的。其中索引的创建是查询优化的前提，
本文对索引的创建提出了一些具体的建议。而对于不良的SQL语句的优化是本文的重点。
因此对SQL语句的优化，本文举出了大量的例子用来说明如何优化和对比优化后的效果。

As to huge database of the data amount, the inquiry velocity difference between inferior SQL sentence and high-quality SQL sentence can be in order to reach dozens of very to hundreds of times. In practical application, one inquire system to just realize his function briefly, but the speech as to some inquiry systems needing to respond in real time, it causes performance to be low if because there is not high-quality SQL sentence, it is pointless even can realize its function. SQL inquires the essence optimized is base on the premise that the result is correct. The optimizing device improves the efficiency of finding out according to the index defined, use SELECT sentence optimized, try hard to avoid the emergence that the whole form scans, improve the inquiry velocity, improve working efficiency. This text proceeds from establishment of the index and optimization of SELECT sentence. Among them the establishment of the index is to inquire about the prerequisite optimized, this text