Tsarin Multivalued Dependency in Design Database

Ƙaƙwalwar ajiya na al'ada ta karya kashi na hudu

A cikin bayanan dangantaka, mai dogara ne yakan faru lokacin da bayanin da aka adana a ɗayan ɗakin labaran ɗin ɗaya yana ƙayyade sauran bayanan da aka adana a cikin teburin guda. Ƙarƙiri mai sauƙi yana faruwa a yayin da gaban ɗaya ko fiye layuka a tebur yana nuna kasancewar ɗaya ko fiye da layuka a cikin wannan tebur. Sanya wata hanya, siffofi guda biyu (ko ginshiƙai) a teburin masu zaman kansu ne na juna, amma dukansu sun dogara ne akan sifa na uku.

Ƙarƙashin daɗaɗɗen yawa yana hana daidaitattun tsari na hudu (4NF). Bayanai na dangantaka sun bi siffofin biyar da suka wakilci jagororin don zane rikodin. Suna hana sabuntawa da rashin daidaituwa a cikin bayanan. Hanya na hudu na yau da kullum yana hulɗa da dangantaka tsakanin mutane da yawa a cikin bayanai .

Matsayi mai aiki tare da shi

Don fahimtar dogara mai yawa, yana da mahimmanci don sake duba abin da aikin dogara yake.

Idan wani sifa na X yana ƙayyade wani sifa Y, to, Y yana aiki ne akan X. An rubuta wannan a matsayin X -> Y. Alal misali, a cikin ɗaliban Students a ƙasa, ɗayan Student_Name ya ƙayyade Maɗaukaki:

Wannan dogara na aiki zai iya rubuta: Student_Name -> Manya . Kowace Student_Name ya ƙayyade ainihin Manya, kuma ba haka ba.

Idan kana so database don kula da wasanni da waɗannan ɗaliban suka ɗauka, za ka iya tunanin hanya mafi sauki da za a yi wannan shine kawai ƙara wani shafi mai suna Sport:

Matsalar nan shine cewa duka biyu Ravi da Bet suna wasa da wasanni masu yawa. Wajibi ne don ƙara sabon layi don kowane ƙarin wasanni.

Wannan tebur ya gabatar da goyon baya mai yawa saboda manyan da wasanni masu zaman kansu ne amma dukansu sun dogara ne a kan ɗaliban.

Wannan misali ne mai sauƙi kuma mai iya ganewa sauƙi, amma dogara mai yawa zai iya zama matsala a cikin babban ɗakun bayanai.

An kwantar da mutunci mai yawa da aka ƙaddara shi X -> -> Y. A wannan yanayin:

Student_Name -> -> Manya
Student_Name -> -> Wasanni

An karanta wannan ne a matsayin "Student_Name da yawa" da "Student_Name multidetermines Sport".

Dogaro da yawanci yana bukatar akalla halaye guda uku saboda ya ƙunshi akalla halaye biyu waɗanda suke dogara da na uku.

Tsarin Multivalued Dama da Daidaitawa

Tebur tare da goyon baya da yawa ya keta daidaitattun ka'idodi na hudu (4NK) domin yana haifar da sakewa da ba dole ba kuma zai iya taimakawa zuwa bayanai marasa daidaituwa. Don kawo wannan har zuwa 4NF, yana da muhimmanci don warware wannan bayanin a cikin tebur biyu.

Tebur da ke ƙasa a yanzu yana da goyon baya na aiki na Student_Name -> Babban, kuma ba'a dogara da nau'ikan nau'i nau'i:

Duk da yake wannan tebur yana da nauyin dogara guda ɗaya na Student_Name -> Wasanni:

A bayyane yake cewa ana daidaita sau da yawa ta hanyar sauƙaƙe ɗakunan Tables masu mahimmanci domin su ƙunshi bayanin da ya shafi wani ra'ayi ɗaya ko jigo maimakon maimakon ƙoƙarin yin tebur guda ɗaya ya ƙunshi bayanai masu yawa.