A abaningi-kokuningi: Isibonelo Finyelela, e-SQL. Indlela yokwenza eziningi-to-?

Zonke DBMS (semininingwane management system) , kukhona izinhlobo eziningana ubudlelwano phakathi amatafula. Phakathi kwabo okukodwa-eyodwa,-kokuningi, abaningi-kokukodwa (abanye bavame ukubona lezi zinhlobo ezimbili zibe uhlobo olulodwa) futhi abaningi-kokuningi. Isibonelo salokhu kwamuva, futhi incazelo yokuthi isebenza yolwazi ehlukene, ezifana Ukufinyelela noma SQL, kuzoxoxwa ngakho kulesi sihloko.

definition

Abaningi-kokuningi ubuhlobo kuchazwa njengendlela umdlalo kunoma yikuphi amakhophi elinye Uketshezi zonke ezinye izimo. Ngamanye amazwi, insimu (wesibili) ithebula lokuqala nawo wonke amasimu wesibili (kuqala) ngamunye.

Leli cebo ibonisa ngokucacile okushiwo lobu buhlobo.

Lapho abaningi-kokuningi ubudlelwano ingasetshenziswa?

Isibonelo eziningi-kokuningi - iqembu umfundi futhi iqembu othisha. Umfundi ngamunye ifunda ngesikhathi esisodwa ngendlela osolwazi ezimbalwa, owavele, anikeze izinkulumo abafundi eziningana. Kulesi sithombe sikhombisa umehluko phakathi okukodwa-abaningi-kokuningi.

Abaningi-kokuningi ubuhlobo Ngokuvamile kuye kudingeke ekulungiseleleni emikhulu yolwazi, izibonelo encane engokomfanekiso okuvame ukusetshenziswa kuphela ngezinjongo zokufundisa, empeleni, practice kuvela ukuthi izinhlangano ngaphezulu database nobudlelwano phakathi kwabo - kulapho amathuba Sokuzivikela njalo abaningi-kokuningi.

Indlela yokwenza eziningi-to-?

Izibonelo ubuhlobo okukhulunywa isazoqhubeka ungeze ngokuhamba ngawo esihlokweni, kodwa kubalulekile ukuba ningabi nje kuphela siyiqonde ukuthi iyini, kodwa futhi ukuthi kusetshenziswe kanjani ke. Yekuchumana yale nqubo kuxhomeke ngqo semininingwane ekhethelwe emisebenzi, ekubeni inikezela isimiso uhlala zonke efanayo.

Microsoft Finyelela

isofthiwe Office kusuka "Microsoft" is emakethe isofthiwe eyaziwa u-Adalberto isikhathi eside. Senziwa sombhalo Worfd, Excel processor tabular kanye nezinye okuqondene ulayini "ihhovisi". Ungakwazi Finyelela (funda ngokuthi "acces", inguqulo yezwi nezwi - "ukufinyelela") ukuthenga futhi behlukile "nozakwethu" yakhe. Kunconywa ukuthenga Yiqiniso, zesofthiwe ezinelayisensi, kodwa akuyona imfihlo ukuthi singakanani repack pirated ingatholakala kuwebhu inkulu, ngesimo amafayela njalo, noma nezifufula izandla. "Microsoft Acces" itholakala ngisho umhlangano ephathekayo. Akudingi ukufakwa futhi noma yimaphi amakhono akhethekile ukuba asebenze nge PC, ke kangcono Ukukhetha uma isofthiwe ngeke isetshenziselwe okuhlala isikhathi eside nokuyingozi ngokuvamile.

Kusukela umongo kuyacaca ukuthi "Microsoft Acces" - a uhlelo lokuphathwa egciniwe. Futhi omunye ethandwa kakhulu. Kuyinto zingubudlelwane okusho ukuthi isekelwe okunengqondo imodeli idatha, okuyinto ngokuhamba umsebenzi wakhe libhekisela theory isethi kanye lokuqala oda logic. Abaningi-kokuningi ubuhlobo e Ukufinyelela (izibonelo uzonikezwa ku incazelo) yaqaphela kakhulu, silula. Cabanga-ke.

Kukhona izibhebhe zombili ..

Ukuze benze noma yini entsha, thatha sekushiwo ukuchaza isibonelo eziningi-kokuningi mayelana nabafundi. Kufanele udale ithebula "Abafundi" futhi etafuleni "Othisha." Kokubili sokuqala nesesibili lawa okhiye eyinhloko. futhi udinga esinye etafuleni, yiziphi izinkambu ngoba ngokuhlanganisa izimo izinhlangano ezimbili - izihluthulelo amatafula lokuqala nelesibili.

Uma sicabanga ngesibonelo esihlukile: ake sithi, abadlali kanye nethimba (inikezwe yokuthi okungenani omunye abadlali amaqembu ehlukene, futhi ngamunye ithimba yakhiwa abadlali nanye), wakha uxhumano ngeke kushintshe. Bazodinga futhi amatafula amathathu. Kulaba bafundi, "Ibhola" futhi "Ithimba" njengoba main nokukodwa Lesisemkhatsini.

uhlelo idatha

Ubudlelwano phakathi amatafula database "Microsoft Acces" yilo Mnyango usebenzisa amandla ithebhu "Idatha Scheme". Isibonisi iphaneli sengezwe zonke izinhlangano (kuleli cala, onke amatafula amathathu). Dala-kokuningi ubuhlobo eziningi-kokuningi uzobe usebenzisa ubudlelwano kabili phakathi kwamadoda avelele ( "Abafundi" futhi "Othisha") futhi etafuleni zesiteji. Ukuze wenze lokhu, kumele kuchunywa okhiye abafanele eyinhloko.

Lomfanekiso ngenhla kubonisa indlela "wesifunda idatha" ithebhu (Relathionships). Isibalo ukungezwa ibhodi ithebula unomphela. Indawo kuyinto adjustable ngokugcwele ngumsebenzisi.

SQL

Database Design ku SQL - umsebenzi kunokukwenza ukuba "Acces". Uma maykrosoftovskih mkhiqizo ngokugcwele bazivumelanisa imvelo ehhovisi, unendawo enkulu lapho futhi, nge ukukhululwa ngamunye futhi ubuyekeze konke ukusebenza Olwandisekayo, kodwa ngesikhathi esifanayo esilungele elula interface yomsebenzisi, SQL - it is a non-zenqubo ulimi lokwakha ehlukile, ngawo ezisekelweni ezahlukene ungasebenza yolwazi. Isofthiwe owaziwa ngokuba lo msebenzi: Oracle MySQL futhi DB2 (a ethandwa, kodwa hhayi kuphela into efana nayo). Naphezu kweqiniso lokuthi ngamunye wabo siqonde izici zaso ezicashile kanye umehluko wemisindo nemiqondo yamagama, ulimi SQL kuyinto zabo 'bahlangene ". Ngokufunda ukusebenza okungenani omunye wabo, ukusebenzelana nabanye kuyoba lula kakhulu.

Dala, ugcwalise nezenzo ngqo kwi database ekhona e SQL ezidingekayo ngokusebenzisa ikhodi ekhethekile noma okulotshiwe. Nokho, labo abenze kakade ke esigabeni "abaningi-kokuningi", isibonelo kule ulimi lokwakha unikezwa ngezansi, kumelwe bazi okungenani imiyalo eziyisisekelo kanye nezimiso ulimi SQL.

Isimiso yokudala eziningi-kokuningi

ukubusa isikhathi eside zibangele amahloni abanye futhi "yilo inkungu", kodwa eqinisweni isimiso ukuqaliswa zokuxhumana ayiguquki. Ukuze uthayiphe ubuhlobo eziningi-kokuningi seyenziwe practice, hhayi kuphela e-"Acces", kodwa futhi SQL, kudingeka ekuqaleni ukudala isizinda amatafula amabili eyodwa - Lesisemkhatsini. Ngokufanayo, kuba ukhiye: ubunjalo eyisiqalo amasimu esemqoka, ngalinye elikwazi silotshwe ithebula ukuxhumanisa. Okuchaza ukuthi ubudlelwano SQL-abaningi-kokuningi akuzona bahluke kusukela "Acces".

Ukwenza umsebenzi we-zokuxhumana

Ukuze siqalise eziningi-kokuningi e iskripthi SQL usebenzisa okhiye yangaphandle (KEY ESIKHONA) efana ukhiye yasekuqaleni ethebuleni main. Baloba kanye yonke imikhakha uma udala kanye / noma ukuhlela.

Indima edlalwa kwabaningi--abaningi

Ngokuvamile, ubudlelwane phakathi izinhlangano e- database ezisetshenziselwa ubuqotho ulwazi olugcinwe kwi-kubo. Yodwa a semininingwane eziklanywe kahle nazo zonke uxhumano kudingekile kuqinisekisa isitoreji ephephile, isipiliyoni umsebenzisi futhi isakhiwo olumelana amathonya zangaphandle kanye nezinguquko. Ngokuvamile, uma egciniwe iqukethe idatha kwi inhlangano yonke, inkampani noma ifemu, iqukethe iqoqo izinhlangano izimo ezahlukene.

Lokhu kusho ukuthi ekulungiseleleni lezi zinhlelo ( "Acces") noma ukubhala izikripthi (in the "Oracle" noma "DiBiTu") uzoba khona okungenani oyedwa abaningi-kokuningi. Isibonelo SQL, ngokuvamile sisetshenziswa ukuqeqeshwa Yiqiniso "Database Inhlangano" - DB King.

Base idatha YeNkosi

I database ukuqeqeshwa ulwazi olumayelana King corporation. Phakathi amatafula:

• izisebenzi zale nkampani - iqukethe ID yesisebenzi, isibongo, igama lokuqala phakathi kokuqala (gxila amagama angaphandle), futhi ikhodi boss kanye nomsebenzi matasa isikhundla, usuku yokwemukela amafemu athole umholo wabo nokuthunywa enikeziwe, ikhodi umnyango;
• neminyango bezinkampani - phakathi emasimini itafula ube ikhodi bese igama umnyango, kanye ikhodi indawo yayo;
• ukubekwa neminyango, okuhilela ngokufaka ulwazi ukubekwa ikhodi kanye negama lomuzi;
• isikhundla kule nkampani - itafula elincane nge izinkambu ezimbili ukuthumela ikhodi bese igama layo esemthethweni;
• amafemu-abathengi - Amasimu: ikhodi bese igama umthengi, ikheli, idolobha, izwe, nekhodi ye-zip nekhodi lendawo, inombolo yocingo, umphathi inkonzo ikhodi ikhasimende, udumo ngenxa yokushintsha umthengi namazwana (amazwana amanothi);
• izivumelwano ukudayiswa, eliqukethe ikhodi kanye nosuku yesivumelwano, ikhodi umthengi, ukulethwa usuku isamba inkontileka;
• Izenzo yokuthengisa - nesenzo ikhodi kanye nekhodi yesivumelwano, okubandakanya isenzo, ikhodi umkhiqizo, intengo yayo, ubuningi ethengwayo kanye Imininingwane ukuthenga izindleko;
• Izimpahla - igama ikhodi komkhiqizo;
• Intengo - ikhodi umkhiqizo, yamemezela kuye intengo, ephansi kungenzeka intengo, usuku lokusungulwa futhi usuku intengo yokukhansela.

Itafula elincane etholakalayo lapho amasimu akukho kuka ezimbili noma ezintathu ezihlobene nabantu abafika ku ithebula nomuntu othile noma eyodwa-kokuningi.

Scale etafuleni elifanayo, ezifana "izisebenzi zale nkampani", "inkampani-abathengi", "izivumelwano ukudayiswa" futhi "izenzo yokuthengisa" ahlanganiswa nesihlalo izinhlangano eziningana, nabanye - ngosizo "abaxhumanisi" Ubuhlobo eziningi-kokuningi. Ithebula "abathengi inkampani" ngokwaso nomlomo, njengoba enjalo, ngoba abaningi emkhakheni, othathwe nezinye kumathebula ukhiye angaphandle. Ngaphezu kwalokho, isikali nokuhlobana semininingwane "Inkosi Corporation" iwukuba zonke buhlobo isici kwehlisa nomunye futhi kuthinte komunye nomunye. Ukubhujiswa okungenani omunye wabo kuzoholela ukubhujiswa ubuqotho lonke database.

ezicashile ezibaluleke

Lapho kwetfula eziningi-kokuningi, kungakhathaliseki ukuthi iyiphi ngabaphathi semininingwane uhlelo isetshenziswa, kubalulekile ukucacisa okhiye lesifanele ngawo utawubhalwa sengqondo. Iqalise ngokungalungile uxhumano akagcwalisi injongo yayo eyinhloko - okungukuthi, ukuqinisekisa ubuqotho etafuleni, futhi ngenxa yalokho, esikhundleni induduzo olulindelekile, umsebenzisi uzothola, ngakolunye uhlangothi, ngokuphazamisa futhi izinkinga ezengeziwe, lezizifo sizibona ikakhulukazi ngesikhathi ngokugcwalisa yokuhlela amatafula nedatha yawo.