一個具有模糊查詢能力之物件導向資料庫查詢語言(EQLf)的設計與製作

Abstract

有鑑於資訊科技應用的普及，使用者與電腦間的溝通介面也越來越 具親和 性。對於資料庫的使用而言，查詢語言就扮演著使用者與資料 庫間最重要的溝通 工具。為能夠讓資料庫查詢語言更具有親和性，讓 使用者能夠更輕易方便的使用 資料庫，一個很重要的關鍵就是擴充資 料庫查詢語言的功能，讓它具有接受與解 釋不精確查詢條件的能力。 本研究的目的就在設計與製作一個在物件導向資料庫上具有描述不精確查 詢條件之查詢語言。在論文中，首先，我們探討一些關於處理不精確查詢 的相關 研究。這些研究根據解釋不精確條件的方式，可以分為相對式 和絕對式兩種方 法。絕對式解釋方式根據所應用之理論又可以分為 兩類，一類為以傳統明確集合 理論(Crisp Sets Theory)為基礎的解 釋方式，另一類為以模糊集合理論(Fuzzy Sets Theory)為基礎的解 釋方式。然後，我們分析與討論這些方法的優缺點，選 擇絕對式中以 模糊集合為基礎的解釋方式，來設計我們自己的查詢語言。基本的 方 法是擴充一個現有的物件導向資料庫查詢語言EQL(An Easy-to-Use Query Language for Object-Oriented Databases[1])，讓它具有描述不精確查 詢條件 的能力，並且對於每一種不精確的查詢提出其解釋方式。最後 ，在製作部份我們 採用物件導向軟體工程之技術並配合視窗介面之程 式設計，來完成一個在使用和 學習上親和性都極佳之模糊查詢語言， 我們將其命名為EQLf (An Object-Oriented Database Query Language for Fuzzy Querying)。 With the popularity of applied information technology, the user interface that acts the role for communications between the users and the computers has been designed to be more and more friendly. For usres who want to access a database, the query language fits as the most important user interface. To make the query language more user-friendly, an important issue arised is to extend the query language with the functionality to accept and explain imprecise queries. The goal of this research is to design and implement an object- oriented database query language for fuzzy querying. In the thesis, we survey some researches on processing of imprecise queries. According to the way to interpret the imprecise constraints, these researches can be divided into two categories: the ones based on relative interpretation and those based on absolute interpretation. The latter ones are divided furthermore into two types by the based theory: those based on crisp sets theory and those based on fuzzy sets theory. After analyzing the advantages and disadvantages of these methods, we choose the absolute interpretation method with fuzzy sets theory to design our query language, which is named EQLf(An Object- Oriented Database Query Language for Fuzzy Querying). EQLf is accomplished by extending an existing query language, namely EQL(An Easy-to-Use Query Language for Object-Oriented Database[1]) to incorporate the capabilities of expressing imprecise predicates and making imprecise queries. By adopting object-oriented engineering technology and windows programming paradgim, EQLf is implemented to validate its excellence in being both user-friendly and easy to learn.