如何加速SQL的运行

HOW TO ACCELERATE SQL′S EXECUTION

SQL语言已成为众所公认的标准数据库语言 ,它对数据库提供了丰富的操作命令 ,尤其是在查询方面。但人们在使用SQL时往往会陷入一个误区 ,即太关注于所得的结果是否正确 ,而忽略了不同的实现方法之间可能存在的性能差异 ,这种性能差异在大型的或是复杂的数据库环境中表现得尤为明显。不良的SQL往往来自于不恰当的索引设计、不充分的连接条件和不可优化的where子句。在对它们进行适当的优化后 ,其运行速度可以有明显地提高 !

As we all know, SQL Language is a standard database language. It provides datatase with rich operational command, especially in query area. However, people are often trapped into a wrong side when they use SQL, that is they pay more attention to the result and neglect that different aapproaches will leda to different qualities. This quality′s difference is very apparent in large or complicated database environment. Bad SQL often comes from improper index desigh, imsufficient join, and unable optimized ‘where’ sentence. After optimizing bad SQL, we can accelerate SQL′s execution.