组合查询的组合算法

Combinational Algorithm of Combinational Query

在数据库运用中,多重条件查询运用越来越普遍,多重条件必须按照一定规则组合才能使查询得出正确结果,而组合方式可能有许多种,到底哪一种组合更优呢?这就是该文要探讨的问题。文章先分析了组合查询的层次性,进而介绍了一种能定量比较查询效率的算法——组合查询树算法,该算法通过计算比较组合查询树的带权路径长度有效地度量每一种组合。

Mutiple condition query is used widely in database.Only when mutiple co ndition query must be combined according to certain rule,correct query result c an be getten.But it have many combination rules,which is better?It is the qu estion to be discussed in this paper.In this writing,combinational hierachical of combinational query is analysed,then combinational query tree algorithm is introduced-an algorithm can compare query efficiency quantifily.The algorithm can measure every combinational by calculating and comparing weighted path lengt h of combinational query tree.