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關(guān)系模式算法設(shè)計(jì)
畢業(yè)論文
摘 要
數(shù)據(jù)庫(kù)技術(shù)是計(jì)算機(jī)科學(xué)中發(fā)展最快的領(lǐng)域之1，也是應(yīng)用最廣的技術(shù)之1，它已成為計(jì)算機(jī)信息系統(tǒng)與應(yīng)用系統(tǒng)的核心技術(shù)和重要基礎(chǔ)。數(shù)據(jù)庫(kù)設(shè)計(jì)是數(shù)據(jù)庫(kù)應(yīng)用系統(tǒng)設(shè)計(jì)的重要步驟,數(shù)據(jù)庫(kù)是否適合應(yīng)用系統(tǒng)的設(shè)計(jì)是至關(guān)重要的，為了使數(shù)據(jù)庫(kù)設(shè)計(jì)方法走向完備，人們研究了規(guī)范化理論，主要通過(guò)討論1個(gè)關(guān)系屬性間不同的依賴情況，討論如何根據(jù)屬性間依賴情況來(lái)判定關(guān)系是否具有某些不合適的性質(zhì)，關(guān)系數(shù)據(jù)中的關(guān)系是要滿足1定要求的，滿足不同程度要求的為不同范式。本文討論的是給出1個(gè)范式，判定是那1種范式。 本文在函數(shù)依賴的范疇內(nèi)對(duì)關(guān)系模型的規(guī)范化理論及其運(yùn)用問(wèn)題進(jìn)行了探討，對(duì)2NF,3NF,BCNF范式進(jìn)行了研究，實(shí)現(xiàn)了上面3種范式的自動(dòng)生成算法，簡(jiǎn)化了范式的判定難度。系統(tǒng)地提出1整套使用地關(guān)系規(guī)范化地具體方法和步驟，給出了1個(gè)判定關(guān)系模式是否屬于其中1種的算法。根據(jù)本文提供的方法可以容易判斷1個(gè)關(guān)系模式，從而避免了因?yàn)閿?shù)據(jù)庫(kù)設(shè)計(jì)不當(dāng)而對(duì)數(shù)據(jù)庫(kù)管理系統(tǒng)造成的影響。
關(guān)鍵字：函數(shù)依賴；候選關(guān)鍵字；閉包；傳遞依賴。
Abstract
The technology of the database is one of the fields with the fastest developing speed in computer science, using one of the widest technology too, it has already become information system of the computer and the key technology of the application system and important foundation. Data design of storehouse whether database use important step that system design, database suitable for design of application system essential, in order to make the database design method move towards being complete, people have studied the standardized theory, one relation different reliance situation under attribute through discussion, discuss how rely on situation is it judge according to attribute relation have some improper nature to come mainly, concern relation of data to meet certain demand ,meet demand in various degree different normal form. What this text discussed is to provide a normal form ,judge which is it Normal form.Within the category of function dependency，the theory and application of normalization of relation model are studied. a set of practically specific methods of relation normalization are systematically put forward. To the 2NF, 3NF,the type of BCNF carried on a research, carrying out a top is three kinds of calculate ways with automatically born modeltypes, simplified the model type to judge a difficulty. And a polynom ial time algorithm to decide whether a relation model is in them given. And provide a arithmetic of determinant a relation pattern is or not pertain to bcnf. Using the way of this artrcle we can easy judge a relation mode, accordingly avoid the influence of unsuitable designing database.
Keywords : Function relies on ; Candidate key word ; closure ; Transmit and rely on.
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