Ukuxhomekeka kokuSebenzayo kunceda ukuphepha ukuphindaphinda kwedatha
Ukuxhomekeke kumsebenzi kwiziko ledatha kukhuthaza isethi yeengxaki phakathi kweempawu. Oku kwenzeka xa omnye umxholo ohambelana ngokukhethekileyo omnye umxholo. Oku kunokubhaliweyo A -> B okuthetha ukuba "B isebenza ngokuxhomekeke ku-A." Oku kubizwa nangokuxhomekeka kweenkcukacha .
Kule lamano, i-A imisela ixabiso leB, ngelixa iB ixhomekeke ku-A.
Kutheni ukuxhomekeka kokuSebenzayo kubalulekile kwiDatabase yeDatabase
Ukuxhomekeka kokusebenza kunceda ukuqinisekisa ukusetyenziswa kwedatha. Cinga itafile Abasebenzi abaluhlu lweempawu ezibandakanya iNombolo yoKhuseleko loLuntu (SSN), igama, umhla wokuzalwa, idilesi njalonjalo.
I-attribute ye-SSN iya kugqiba ukubaluleka kwegama, umhla wokuzalwa, idilesi kwaye mhlawumbi nezinye ixabiso, kuba inombolo yokhuseleko yoluntu iyingqayizivele, ngelixa igama, umhla wokuzalwa okanye idilesi ayinakho. Singayibhala njengale:
SSN -> igama, umhla wokuzalwa, idilesi
Ngoko ke, igama, umhla wokuzalwa kunye nedilesi zixhomekeke kwi-SSN. Nangona kunjalo, isitatimende esilandelayo (igama -> SSN) aliyinyaniso kuba abasebenzi abangaphezu kweyodwa bangaba negama elifanayo kodwa abayi kuba ne-SSN efanayo. Beka enye indlela, engakumbi, ukuba siyazi ukubaluleka kwempawu ze-SSN, sinokufumana ixabiso legama, umhla wokuzalwa kunye nedilesi. Kodwa ukuba endaweni yoko siyazi ixabiso legama nje kuphela, asikwazi ukuchonga i-SSN.
Icala lasekhohlo lokuxhomekeka komsebenzi lingaquka into engaphezulu kweyodwa. Masithi sinezoshishino ezineendawo ezininzi. Singaba neetafile Umqeshwa kunye neempawu zomsebenzi, isihloko, isebe, indawo kunye nomphathi.
Umqeshwa unquma indawo asebenza kuyo, ngoko kukho uxhomekeke kuye:
Umqeshwa -> indawo
Kodwa indawo ingaba nomphathi omnye, ngoko umqeshwa kunye nesebe badibanisa umphathi:
Umqeshwa, isebe -> umphathi
Ukuxhomekeka kokuSebenzayo nokuQinisekisa
Ukuxhomekeka kokusebenza kuncedisa kwizinto ezibizwa ngokuba yi-database yolwazi, eqinisekisa ukuthembeka kwengcaciso kunye nokunciphisa ukuhlengahlengiswa kwedatha. Ngaphandle kokuqhelanisa, akukho siqinisekiso sokuba idatha kwiziko elichanekileyo lichanekile kwaye linokuthenjwa.