DB - ke ... Izinhlobo nezakhiwo database

DB - emelela ukuthi imele "semininingwane" noma "semininingwane" (kuye ngomongo). Kulesi sihloko, sicabanga ukuthi / abayikho, iziphi futhi kuphi isicelo. Futhi ukuxoxa DBMS kanye database - ke kuyafana noma cha.

amagama

Database okukhulunywe ezithile Igumbi ehlelekile kolwazi. DB - liphinde imodeli ulwazi, ikhono aqukethe idatha ethile, nge amalunga bayobizwa ngaphambilini. Ngamunye umsebenzi wethu database okungenani kanye, kodwa abakwazanga ngisho ukuqagela, isibonelo, ngokufaka itemu, siphendukela emikhulu isisekelo idatha ethile ulwazi.

DBMS - kungenye emelela, esimelela "ngabaphathi semininingwane uhlelo". Ngomqondo obanzi, abakubonisayo izingxube ezihlukahlukene zoketshezi isofthiwe, ngawo ungakwazi ukuhlela idatha egciniwe. Lokhu kusho ekugcwaliseni base ulwazi, wayala-ke, ukususa, ukukopisha, ukuhlaziywa nokunye okuningi.

Amafomu semininingwane

Ngo semininingwane ithiyori, kunezinhlobo eziningana zazo. kukhona:

• yolwazi zingubudlelwane (kusukela lesiNgisi elithi maqondana, okuyinto uhumusha njengoba "uxhumano") - zinezikhathi ubudlelwane futhi wezwakalisa njengoba iqoqo izinhlangano kuhlobene. Lesi sakamuva ethulwa ngesimo amaphilisi, aqukethe imininingwane egciniwe. Lona ezivamile uhlobo egciniwe.
• Phezulu - ngenxa ezingeni "komzali nengane", "aphakeme-okhonzile".
• Network - nehlumela zilwane odlule.
• Into ngamakhasimende, okuyinto ngqo ne ezifanele izinhlelo indlela (PLO).

Ake sicabangele ngayinye yalezi zinkulumo ngokuningiliziwe, ephumula endleleni wemiqondo eyisisekelo kanye imiqondo of database.

DB - liyisibonakaliso?

yolwazi zingubudlelwane kukhona e ukumelwa kwabo evamile akakubangeli nobunzima ngokuqondisisa - uqwembe ngolwazi. Ukuze sicacise, ungabiza usizo egciniwe owaziwa kakhulu izinkampani "Microsoft" - "Acces", ingxenye evamile zabo zokusebenza ehhovisi iphakethe.

Ngo zingubudlelwane semininingwane amatafula abe okufakiwe (imigqa) namasimu (amakholomu). Owokuqala uqukethe ulwazi ngokushesha, idatha esikhathini esidlule - incazelo yokuthi kusho ukuthini ukurekhoda. Ngokwesibonelo, ensimini - "igama" entry - "Catherine".

Ukuze Amasimu kuchazwe value izinhlobo. Kungenzeka ezinombolo, uhlamvu, usuku, isikhathi, njll Futhi, lamatafula kufanele kube ensimini ukhiye - .. Qopha therein ngokuhlukile idatha.

Kufanele kuqondwe ukuthi database ngokwayo - akusiyo itafula. I database zingagcinwa komunye ematafuleni abangamakhulu amaningana, kuye ngokuthi lemali nokwehluka ulwazi.

Ubudlelwano phakathi amatafula

Ukuqinisekisa ubudlelwano phakathi amatafula database has a schema. Wezokuxhumana yilena:

• "Omunye-kokukodwa" - irekhodi ngayinye kulelithebula oluhambisana irekhodi elilodwa kuphela kusuka kwenye ipuleti.
• "Omunye-kokuningi" futhi "abaningi-kokuningi". Record kungase kungahambisani eziningana etafuleni ezihlobene. Kungenjalo (samuntu yesibili).
• "Abaningi-kokuningi". Akunzima ukuqagela ukuthi kuleli cala, imigqa multiple kungenziwa kukhethwe ukuxhuma imigqa multiple lomunye etafuleni (isixhumanisi enjalo ihlelwe usebenzisa itafula zesiteji nezixhumanisi ezimbili ngenhla zinhlobo).

Ukuhambisa phezulu naphansi

egciniwe phezulu zakhiwe okuningi kuka zingubudlelwane. Avame ukulalela esiqinile. Kukhona element impande - the "ithiphu", okuyinto igatsha off abangaphansi - "izindlalifa" noma "inzalo". egciniwe phezulu - isisekelo kokuba isakhiwo isihlahla lapho amadlozi eyodwa kuphela kungenzeka engeyokuqala ngalinye.

Lolu hlobo Kuyinto elula ukusebenzisa lokwakha ekhosombeni kolwazi kakade wase uyale isakhiwo: isibonelo, base Abezempi noma ifayela idatha umphathi. Ububi kubhekwa ingenzeki iyunithi engaphezu kweyodwa umzali, kanye yinkimbinkimbi logic egciniwe.

ukwandisa ubudlelwane

Uxhumano DB steel isinqumo yokuntuleka phezulu elishiwo ngenhla nje. "Abaningi-kokuningi" Umehluko kuphela phakathi lolu hlobo ubuhlobo odlule saqala, lokukhulunywa ngako kulendzaba iboniswa iqiniso lokuthi njengoba ngukhokho kungase kudingeke izindlalifa eziningi, futhi babezazi, inzalo, singenzeka kusukela ISIZINDA eziningana.

Tabular ukubonisa indlela

Naphezu kweqiniso lokuthi amatafula ezihlobene ngokuyinhloko yolwazi zingubudlelwane futhi ephethwe yisigungu sesonto, inethiwekhi, futhi ingafakwa amelwe ngesimo amatafula. Umehluko oyisisekelo phakathi kwalezi zinhlobo - ngokomthetho ukwakhiwa isakhiwo: zingubudlelwane kuqhathaniswa nabanye ababili yayisikhululeke kakhudlwana kakhulu futhi kancane-odile.

Into isitayela ngamakhasimende

Igcine ukubukwa uhlobo - into-ngamakhasimende - okuvame okungenani. Lokhu kungenxa yokuthi kuba ezikhethekile kakhulu. Inxanxathela izakhiwo idatha efana base ifomu umenziwa ngqo ne ulimi izinhlelo into-ngamakhasimende. Bona ezakhiwa Eighties kwekhulu elidlule kanye angakawamukeli ukuthandwa kakhulu ngoba yokuthi liyinkimbinkimbi ngendlela futhi ulinganisele hhayi eliphezulu kakhulu ijubane.