Tsari irin na danniya data model

Abubuwan suna sosai sau da yawa samu a irin wannan dangantaka, wadda ake kira matsayi. Yawancin lokaci da ta je irin wannan dangantaka, kamar yadda "part-duka", da aboki na karkashi ko irin dangantaka. Abubuwan da suke a irin wannan dangantaka, ya samar da wata itãciya, wanda aka kira a directed jadawali, wato, da ciwon daya kawai kokuwa ba subordinated zuwa wani kokuwa. Wannan kumburi da aka kira da tushen da itace. The hulda tsakanin sauran nodes aka aiwatar kamar haka: wani kokuwa ne batu kawai ga wanda located sama da shi, saman. Conceptually, da matsayi data model aka fahimci matsayin sa na rikodin iri da cewa suna da alaka da iri sadarwa cikin guda ko 'yan mutum itatuwa. A wannan model, iri daban-daban na shaidu suna kafa bisa ga "daya zuwa dama", da kuma jadawali aka wakilta kibiyoyi. Sai dai itace cewa da matsayi data model yana da irin wannan dangantakar da ke tsakanin abubuwa, duka a cikin iyali itace, duk da haka, daya banda: akwai daya kawai babban batu ga kowane ƙarƙashin abu. Wannan shi ne, a cikin irin wannan data model yarda a yi kawai iri biyu sadarwa tsakanin database abubuwa, "daya zuwa daya" ko "daya zuwa da yawa". The matsayi database a cikin ainihi shi ne wani data tushe na kewayawa, wato, samun mai yiwuwa ne kawai tare da taimakon baya a tsare a tsakaninsu.

Idan da za'ayi taron kwaikwaiyo, sadarwa yawanci bukatar "da yawa ga 'yan." Don cire wannan iyakancewa ba, shi ne zai yiwu a bayar da irin wannan bayani, a matsayin kwafi na wurare. Duk da haka, akwai wani rashin kwafi na abubuwa: da savanin da bayanai iya bayyana. Tsari irin na danniya data model yana da abũbuwan amfãni kamar tabbatar da sauki damar tare da wasu tsararrun links saboda da yanayi kewayawa. Duk da haka, akwai ta kuma rashin amfani. Su kuwa suna da alaka da rashin sassauci a wani data model, musamman kamar yadda Game da rashin yiwuwar gaban abu da dama iyaye, kazalika da rashin iyawa samu kai tsaye dama ga bayanai. Wannan ya jũya shi a cikin wani m cikin sharuddan da na yau da kullum queries da cewa a baya aka ba su shirya. The matsayi model database yana da wani drawback. shi ya ta'allaka ne a gaskiyar cewa bayanai gyara daga cikin ƙananan matsayi matakan ba za a iya aiko da nodes located sama.

Kamar yadda na asali bayanai raka'a a wani matsayi model ne kashi da kuma filin. A karkashin filin data dauka domin sanin da karami basa rabuwa na data cewa shi ne samuwa ga mai amfani. Domin segments dauka domin sanin irin da kashi misali. A kashi irin ne mai suna tarin filayen da bayanai iri, wanda aka hada. Misali kashi kafa daga wasu takamaiman dabi'u na filayen. The matsayi data model, kamar yadda aka ambata a sama, da aka kafa a cikin siffar jadawali data tsarin. Idan muka yi la'akari da shi a matakin da ra'ayi, shi ne kawai musamman hali na cibiyar sadarwa model. A matsayi model vertices dace da kashi irin da arcs - irin sadarwa a wani "iyaye-yaro". Akwai tsananin mulki, a kashi-zuriya iya zama daya kawai m. Kullum, wannan model kama wani undirected alaka jadawali yana da wata itãciya tsarin, yake haɗa kan bangaskiya duk segments. Structure matsayi database irin hada da wani umurni da ya kafa itatuwa. A tsarin da kanta ita wata itãciya, a cikin manya matakin wanda daya ne babban abu sanya a kan na biyu matakin na biyu matakin abubuwa, da uku - uku, da sauransu.

Daga wannan abu, za ka iya samun wasu ra'ayin abin da ya ƙunshi wani matsayi data tsarin.