DB - shi ... The iri da kaddarorin a database

DB - wani acronym cewa tsaye ga "database" ko "database" (dangane da mahallin). A cikin wannan labarin, za mu yi la'akari da cewa shi / su ne, abin da suke da inda ka nema. Har ila yau tattauna da DBMS da database - shi ne guda ko ba.

terminology

Database ake magana a wasu ginannun mangaza na bayanai. DB - shi ne ma wani bayani model, da ikon dauke da wani data, da proviso cewa su za a yi umurni. Kowannen mu ya yi aiki tare da database a kalla sau daya, amma ba zai ko tsammani a da, misali, ta hanyar shiga wani search lokaci, mun tũba zuwa babban-sikelin dalilin takamaiman bayanai data.

DBMS - shi ne wani acronym, wanda tsaye ga "database management system". A wani janar ji, suna wakiltar wani iri-iri na software mafita, tare da abin da za ka iya tsara da database data. Wannan yana nufin cika da bayanai tushe, umurnin shi, sharewa, kwashe, bincike da kuma yafi.

siffofin database

A database ka'idar, akwai da dama iri iri su. akwai:

• Da zumunci databases (daga Turanci kalma aboki, wanda fassara a matsayin "connection") - an halin dangantakar da kuma bayyana matsayin sa na m abokai. A karshen an gabatar a cikin nau'i na alluna, wanda dauke da database data. Wannan ne ya fi kowa irin database.
• Tsari irin na danniya - saboda da matakin na "iyaye-yaro", "m-ƙarƙashin".
• Network - wani offshoot na baya jinsunan.
• Tsargi-daidaitacce, wanda aiki kai tsaye tare da ya dace shirye-shirye hanya (PLO).

Bari mu bincika kowane daga cikinsu, daki-daki, da tsayawa tare da hanyar da asali ra'ayoyi da Concepts a database.

DB - shi ne wata ãyã?

Da zumunci databases ne a cikin saba misali ba sa matsaloli ga fahimtar - a plaque tare da bayani. Don bayyana, za ka iya kiran neman taimako ne sosai sanannun database na kamfanoni "Microsoft" - "Acces", wani ɓangare na su saba ofishin aikace-aikace kunshin.

A da zumunci database alluna da shigarwar (layuka) da kuma filayen (ginshikan). A farko ya ƙunshi bayanin nan da nan, da data a baya - a bayanin abin da ake nufi rikodi. Alal misali, filin - "sunan" shigarwa - "Catherine".

Ga filayen tsare darajar iri. Suna iya zama Tazarar, hali, kwanan, lokaci, da dai sauransu Har ila yau, kowane tebur yana zama a key filin - .. Record cikinta uniquely gane data.

Ya kamata a fahimci cewa database kanta - shi ne ba da wani tebur. A database za a iya adana daga daya zuwa dama da ɗari Tables, dangane da adadin da kuma bambancin da bayanai.

Dangantaka tsakanin allunan

Don tabbatar da dangantaka tsakanin allunan cikin database yana da wani tsari. Communications ne:

• "Daya-to-daya" - kowane rikodin a tebur yayi dace da daya kawai rikodin daga wani farantin.
• "Daya-to-da yawa" da kuma "da yawa-to-da yawa". Record iya dace wa da dama daga cikin alaka tebur. A madadin (na biyu embodiment).
• "Mutane da yawa-to-da yawa". Ba shi da wuya a tsammani cewa, a wannan yanayin, mahara layuka za a iya zaba domin haɗa mahara layuka na wani tebur (irin wannan mahada da aka shirya ta amfani da wani staging tebur da biyu links sama jinsunan).

Motsi sama da kasa

Tsari irin na danniya database ne yafi ginannun fiye da zumunci. Sun ayan tsananin biyayya. Akwai tushen kashi - da "tip", wanda reshe kashe qarqashinsu - "magada" ko "zuriyarsa". Tsari irin na danniya database - mai tushe da ciwon wata itãciya tsarin a wanda daya kawai m iya zama a kowane kumburi.

Wannan irin ne dace don amfani domin ginin da suke riƙe da bayanai riga ya umarci tsarin: misali, da tushe soja naúrar ko da mai sarrafa fayil bayanai. A hasara ne dauke zai yiwu ba ga naúrar a yi fiye da daya iyaye, kazalika da wuya daga cikin database dabaru.

fadada dangantakar

Cibiyar sadarwa DB karfe yanke shawara rashin matsayi mai suna kawai a sama. "Mutane da yawa-to-da yawa" The kawai bambanci tsakanin irin wannan gabata fara hulda da, wanda a cikin wannan yanayin ne aka nuna a gaskiyar cewa matsayin m iya samun dama magada, kuma sũ, a zuriyarsu, na iya faruwa daga dama nodes.

Tabular nuni Hanyar

Duk da cewa allunan suna hade da farko tare da zumunci databases da kuma matsayi, cibiyar sadarwa, kuma za a iya wakilta a cikin nau'i na alluna. A bambanci tsakanin wadannan iri - a manufa da gina tsarin: zumunci, idan aka kwatanta da sauran biyu ne da yawa 'yanci, da kuma kasa da umarnin.

Object daidaitacce style

Last kyan gani, irin - wani abu-daidaitacce - da kalla na kowa. Wannan shi ne saboda yana da matukar musamman. Complex data Tsarin irin wannan tushe nau'i abu da kuma aiki kai tsaye da harshen abu-daidaitacce shirye-shirye. Suka ci gaba a cikin eighties na karshe karni da kuma ba tukuna karbi yawa shahararsa saboda cakuduwar da kuma ba sosai high kudi na gudun.