Network Data Model

Le modyuli yedata womnatha ithatha indawo oluneqela ilula kwaye icacile. Xa ezingundoqo yawo, imodeli womnatha iyafana kakhulu kuluhlu, buye amacandelo, oko kukuthi isiqalelo iingcambu apho igcinwa iinkcukacha ezibalulekileyo. Phakathi kwiindawo kuhlanganiswa ngokusebenzisa amakhonkco. Kwaye iindawo imi kumgama elifanayo engcanjini esiludumbo lokubumba, njengoko le modeli oluneqela elinegunya, amanqanaba. Le peculiarity yemodeli oluneqela yayikukuba ukusuka element enye ukuya kwenye unokuba indlela enye kuphela, yaye olu thungelwano akunjalo, kukho iindlela ezininzi. Le modyuli yedata womnatha kunika ithuba lokwakha izakhiwo ezininzi ezintsonkothileyo lwe data. Oku umahluko ophambili phakathi kwezi mifanekiso mibini.

Ukwenzela ukuba udale i umfuziselo data kwaba ukuqaphela yonxulumano 'abaninzi abaninzi "kunye ngaxeshanye lonke nokulungiswa kokusilela ezikhoyo kwi imodeli oluneqela elinegunya, eziye zachongwa ngokuhamba kwexesha. Le modyuli yedata network isekelwe ukusetyenziswa kwethiyori grafu. Ukusuka lo mbono, siyafana ukuba igrafu ngokwesigqibo esicalanye. Kulo mzekelo, inzala ngalinye linga nenani naliphi na inani izinyanya. database Network siqulathe uluhlu iirekhodi, wathi isethi zezihlobo ezathi akhoyo phakathi iirekhodi data. iintlobo ezimbini kweerekhodi, oko kukuthi ngukhokho kunye nenzala, isigqibo iindidi obuchopho. uhlobo Umzekelo zonxibelelwano ngokuqhelekileyo umele ifunwa ukhokho Ngokushicilela kuqukwa i iseti wayalela lwezinto akwi entry type umntwana. Phantsi iseti ngokuqhelekileyo bendiqonda iseti yeerekhodi, apho uhlobo irekhodi wathi umnini iseti, kunye nezinye iirekhodi - eli iseti amalungu.

Le modyuli yedata lenethiwekhi ezinye izinto awohluke. Zonke iintlobo obuchopho ezisetyenziswayo kufuneka nakanjani babe functional, oko kukuthi, "abaninzi ukuya kwenye", "one-to-inkitha" okanye "enye ukuya kwenye". Le modeli kuphela ngaphakathi wavakalisa Kuluvo ukuba olu hlobo ngokunxulumene uhlobo oluthile irekhodi izinyanya kunye kumnombo uhlobo zokurekhodisha iimeko ngokuyimfuneko ezithile ziyafezekiswa. Ukuze kumiselwe ubudlelwane "abaninzi abaninzi", uhlobo olulodwa kweerekhodi yazisiwe, kwakunye iperi ezisebenzayo link kwefom "omnye ukuya nobuninzi" yaye "abaninzi-to-one." Ukuba kuyimfuneko, ulwazi olongezelelweyo zingadityaniswa kwi khasethi, enza indima nemisipha.

Wobudlelwane Iqela imodeli womnatha zichaza ngokubanzi uhlobo ukuzalana "one-to-iseti", oko kukuthi, umnini omnye, kodwa yena a lot of abangaphantsi. Umntu Yenza umzekelo nesi simo njengokuba "umsebenzi." Apha kuthetha ukuba umqeshwa ngamnye osebenza kuyo naliphi isebe elithile, kodwa zonke isebe ukusebenza kakuhle abasebenzi bambalwa. Uhlobo model inethiwekhi "enye ukuya nobuninzi" ubudlelwane phakathi kumaqumrhu ohlukeneyo iyaphunyezwa ngendlela lobudlelwane qela.

Umfuziselo womnatha database kubandakanya ukusetyenziswa imisebenzi zilandelayo kwi data:

- Khumbula, kufuneka ukuba ufake iinkcukacha database yethu;

- ukubandakanya kwi sengqondo qela, omi phakathi kwezi unxibelelwano ethile;

- utshintsho, loo nto ukuba benze utshintsho bashenxe enye iseti ilungu ukuba nawuphi na umnini;

- update, oko kukuthi, ukuba enze naluphi na ukuguqulwa data;

- Isicatshulwa, oko kukuthi, ukwenza imisebenzi yokufunda data;

- ukususa, oko kukuthi, ukwenza ukususwa ubhalo okanye ngokwasemzimbeni lwe data;

- wayesazi ingxelo nobudlelwano, oko kukuthi, ukuba enze waphula ikhonkco phakathi kwe data.

Xa umfuziselo data okunjalo iimpawu ezizodwa ukuze zisetyenziswe data kunye nokuhamba phakathi kwabo. Iyunithi yokukhangela in imodeli igrafu yokusekwa beerekhodi ofuna ukufaka omnye ngokulungisa data. Ezi rekhodi kuthiwa lwangoku ngokuqhelekileyo. Umfuziselo womnatha inokuba kubakho ukusuka utshintsho ngoku ukuya umzekelo elandelayo esiludumbo yangoku kwenye lwangoku enekona ikhonkco engenasizathu neyathi ndaqonda yi ubudlelwane iqela. Yokukhangela ukuze kuqale nge lokurekhoda ngokwesigqibo esicalanye.