Ukuxhomekeka kwezinto ezixhomekeke kwi-Design Design

Ukuxhomekeke kwezinto ezininzi kunqumla ifom yesine evamile

Kwiziko leenkcukacha, ukuxhomekeka kwenzeka xa ulwazi olugcinwe kwitheyibhile efanayo yedatha lucacisa ngolunye ulwazi olugcinwe kwitheyibhile efanayo. Ukuxhomekeke kwezinto ezininzi kwenzeka xa ubukho bomgca omnye okanye ngaphezulu etafileni bubonisa ukuba kukho enye okanye eminye imigqa kwisebe efanayo. Faka enye indlela, iimpawu ezimbini (okanye iikholam) etafileni zizimeleyo komnye, kodwa zombini zixhomekeke kwisicatshulwa sesithathu.

Ukuxhomekeke ekuxhaseni okuninzi kunqanda indlela eqhelekileyo yesiqhelo sesine (4NF). Iinkcukacha zolwazi zilandela iindlela ezi-5 eziqhelekileyo ezibonisa izikhokelo zokuyila irekhodi. Zithintela ukungahlaziywa kokuhlaziywa nokungahambelani kwidatha. Ifom yesine eqhelekileyo ijongene nobudlelwano obuninzi kwi- database .

Ukuxhomekeka kokuSebenzayo kunye nokuxhomekeka kweMattivalued Dependency

Ukuqonda ukuxhomekeka kwezinto ezininzi, kuyakunceda ukuphinda ubuyekeze ukuba yintoni ukuxhomekeka kokusebenza.

Ukuba isibonakaliso X sichaza ngokukodwa umlinganiselo uY, uY usebenza ngokuxhomekeke ku-X. Oku kubhaliwe njenge-X -> Y. Ngokomzekelo, kubafundi betafile ngezantsi, uMfundi we-Name ubeka uMagosa:

Ukuxhomekeka kokusebenza okunokubhaliweyo kunokubhalwa: Umfundi -Name-> Omkhulu . I-Student_Name nganye inquma ngokukodwa omnye Omkhulu, kwaye akukho.

Ukuba ufuna ukuba isiseko sedatha siphinde silandelele imidlalo aba bafundi bathatha, unokucinga ukuba indlela elula yokwenza oku kukungongeza enye ikholomu ebizwa ngokuba yiMidlalo:

Ingxaki apha kukuba uRavi noBhete badlala imidlalo emininzi. Kubalulekile ukongeza umqolo omtsha kuyo yonke imidlalo eyongezelelweyo.

Le tafile ibonise ukuxhomekeke kwezinto ezininzi ngenxa yokuba ezinkulu kunye nemidlalo zizimeleyo komnye kodwa zombini zixhomekeke kumfundi.

Lo ngumzekelo olula kwaye ukhangeleka kalula, kodwa ukuxhomekeka kwamaninzi kunokuba yinkinga kwi-database ekulu, eyinkimbinkimbi.

Ukuxhomekeke kwezinto ezininzi kubhaliwe X -> -> Y. Kule meko:

Umfundi_Name -> -> Mkhulu
Umfundi_Name -> -> Ezemidlalo

Oku kufundwe njenge "Student_Name multidetermines Major" kunye ne "Student_Name multidetermines Sport."

Ukuxhomekeke kokuxhomekeka kuninzi kubandakanya ubuncinane iimpawu ezintathu kuba ziqukethe ubuncinane ubuncinane ezimbini ezixhomekeke kwisithathu.

Ukuxhomekeka kweMveli kunye nokuQinisekisa

Itheyibhile enokuxhomekeke kwimilinganiselo ephuculweyo iphula umgangatho oqhelekileyo weFom yeSine eqhelekileyo (4NK) kuba idala ukulungelelaniswa okungadingekanga kwaye inokuba negalelo ekuhambeni kwedatha engahambelaniyo. Ukuzisa oku ku-4NF, kuyimfuneko ukuphula le ngcaciso kwitafile ezimbini.

Itheyibhile engezantsi ngoku inokuxhomekeka komsebenzi we-Student_Name -> enkulu, kwaye akukho zixhomekeke ezixhasayo:

Nangona le tafile nayo inokuxhomekeka kokusebenza komfundi we-Student_Name -> yeMidlalo:

Kucacile ukuba ukuqheleka kudla ngokubhekiselele ekululazeni iitheyibhile eziyinkimbinkimbi ukuze ziqulethe ulwazi olunxulumene nombono omnye okanye umxholo kunokuba uzame ukwenza itafile enye ziqulethe ulwazi oluninzi oluchaseneyo.