Database dependencies ne batun da cewa sau da yawa rikice dalibai da kuma kwararrun kwararru daidai. Abin farin cikin, ba su da rikitarwa kuma za'a iya kwatanta su ta hanyar amfani da misalai. A cikin wannan labarin, zamu bincika batutuwa masu dogara na yau da kullum.
Tashoshin Bayanan Cibiyoyin / Mahimmancin Yanayi
Ƙididdiga ta auku a cikin bayanan bayanan bayanan da aka adana a cikin ɗakin labaran ɗin guda ɗaya yana tsara wasu bayanan da aka adana a cikin teburin ɗaya. Hakanan zaka iya bayyana wannan a matsayin dangantaka inda sanin darajar siffar ɗaya (ko saiti na halayen) ya isa ya gaya muku darajar wani nau'i (ko sa na halaye) a cikin teburin guda.
Da'awar cewa akwai dogara a tsakanin halayen a cikin tebur yana da cewa yana da dangantaka da ke tsakanin waɗannan halaye. Idan akwai dogara a cikin ɗakunan bayanai irin wannan batu na B yana dogara ne akan sifa A, za ku rubuta wannan a matsayin "A -> B".
Alal misali, A cikin jerin jerin halaye na ma'aikatan haɗe da Sashen Tsaro na Jama'a (SSN) da kuma suna, ana iya cewa sunan yana dogara da SSN (ko SSN -> suna) saboda sunan mai aiki na iya ƙaddara daga SSN. Duk da haka, bayanin da aka ba da (sunan -> SSN) ba gaskiya ba ne saboda mutane fiye da ɗaya suna da suna daya amma daban-daban SSNs.
Mahimmancin Mahimmancin Yanayi
Matsayi mai banƙyama na aiki yakan faru lokacin da ka bayyana aiki na dogara da wani sifa a kan tarin halaye wanda ya ƙunshi asalin asali. Alal misali, "{A, B} -> B" bashi dogara ne a aikin, kamar yadda "{suna, SSN} -> SSN". Irin wannan nauyin dogara ne ake kira maras muhimmanci saboda ana iya samuwa daga hankula. A bayyane yake cewa idan kun rigaya san darajar B, to, darajar B za a iya ƙayyadewa ta musamman ta wannan ilimin.
Cikakken Kasuwancin Kasuwanci
Kwarewar aikin aiki yana faruwa a lokacin da ka riga ya cika bukatun don dogara da aikin kuma saitin halaye a gefen hagu na aikin sanarwa na aikin ba za'a iya ragewa ba. Alal misali, "{SSN, shekarun} -> suna" yana dogara ne da aikin, amma ba cikakken dogara ne na aikin ba saboda zaka iya cire shekaru daga gefen hagu na sanarwa ba tare da tasiri da dangantaka ta dogara ba.
Tsarin Dama
Hanyoyin haɗari suna faruwa yayin da akwai dangantaka ta kai tsaye wanda ke haifar da dogara ga aikin. Alal misali, "A -> C" yana dogara ne da gaske idan gaskiya ne kawai saboda duka "A -> B" da "B -> C" gaskiya ne.
Ƙididdigar Multivalued
Masu dogara na al'ada sune ke faruwa lokacin da ɗaya daga cikin layuka a cikin tebur yana nuna kasancewar ɗaya ko fiye da layuka a wannan tebur. Alal misali, kwatanta kamfani na mota wanda ke samar da mota da yawa, amma yana sa launin ja da launuka masu launi na kowanne samfurin. Idan kana da tebur wanda ya ƙunshi sunan samfurin, launi da shekara na kowanne motar da kamfanin ke yi, akwai dogara da yawa a wannan tebur. Idan akwai jere don wani samfurin samfurin da shekara a cikin blue, dole ne kuma ya zama irin wannan jimla daidai da ja version of same car.
Muhimmancin Mahimmanci
Bayanan bayanan bayanai suna da muhimmanci a fahimta domin suna samar da ginshiƙan ginin da aka yi amfani dashi a cikin daidaitaccen bayanai . Misali:
- Domin teburin ya zama nau'i na biyu (2NF) , babu wani nau'i na wani alamar maras kyau a cikin teburin da ke aiki da dogara akan wani ɓangare na maɓallin dan takarar .
- Domin teburin ya zama nau'i na uku (3NF) , kowane nau'i mai mahimmanci dole ne ya dogara da maɓallin dan takarar wanda ba shi da tushe.
- Domin teburin kasancewa a Formce Codd Normal Form (BCNF) , kowane dogara da aikin (wanin wajibi ne kawai) dole ne a kasance a kan superkey .
- Don tebur ya zama nau'i na hudu (4NF) , ba dole ba ne a dogara da shi ba.