Yazi ngeli nqaku, eyona nto iphambili Iimpawu zedatha, ulwakhiwo lweetafile zobudlelwane.
Iimpawu zedatha
I-database yobudlelwane yinkqubo elawulwa yimodeli enengqiqo, eyona nto isetyenziswa kakhulu namhlanje kwiinkcukacha ezahlukeneyo eziveliswayo. Xa sibhekisela kwimodeli enengqiqo, sithetha ngemodeli yentlangano egxininisa yonke intlangano kunye nolawulo lwalo kwiinkcukacha ezigcinwe kwiitheyibhile ezenziwe ngemigca (ii-tuples) kunye neekholomu (amasimi).
Le datha yobudlelwane yaqala ukusetyenziswa kwi-1970, umthuthukisi wayo ngu-Edgar Frank Codd, owathi, ngenkxaso ye-IBM, ngokukhawuleza waba sisixhobo esiphambili kule ntsimi.
Phakathi Iimpawu zedatha Ubudlelwane sinako ukubunjwa kwayo, njengoko sele sichazile, ichongiwe ngokuboniswa kwiitheyibhile ezaziwa njengobudlelwane. Ezi theyibhile zinento ekhethekileyo yokuba zizodwa, azinakubakho iitafile ezimbini ezinegama elifanayo okanye irekhodi.
Ubudlelwane obusekwe kwiitafile ezaziwa njengomzali nomntwana ziveliswa ngokubulela kwizitshixo eziphambili kunye nezitshixo zangaphandle. Eyokuqala ivumela ukuba sigcine ingxelo enyanzelekileyo ukuthobela ingqibelelo yedatha. Okubhekiselele kwindlela echanekileyo nepheleleyo yokuzalisa ulwazi koovimba beenkcukacha nokwenza obu bugcisa busebenze ngokubanzi. Ukuba ufuna ukwazi ngakumbi ngesi sihloko, siyakumema ukuba ufake eli khonkco lilandelayo Isebenza Njani Ubuchwephesha?
Ngakolunye uhlangothi, sinezitshixo zangaphandle okanye zangaphandle ezichongiweyo okanye ezaziwa ukuba zisetyenziswe kwiitafile zomntwana, ezo ziqulethe ixabiso elifanayo lezitshixo eziphambili, ezivumela ubudlelwane phakathi kwabo.
Iimpawu eziqhelekileyo
Kubalulekile ukuqaphela ukuba uvimba weenkcukacha wobudlelwane usivumela ukuba sigcine kwaye sifikelele kubudlelwane obahlukeneyo esele bumiselwe kwangaphambili. Yiyo loo nto kubaluleke kakhulu ukwazi uphawu ngalunye lwedathabheyisi, esiza kuyihlalutya nganye nganye. Enkosi ngendlela ebesikhe safumanisa ngayo ngaphambili ukuba nganye kwezi theyibhile yahlukile kwaye ayiphindi iphindeke. Nangona kunjalo, kukho iimpawu eziqhelekileyo ezi:
ubudlelwane basesiseko
Nayiphi na idatabase yobudlelwane inale fomati, kuba yinto esiyaziyo njengetafile. Le nto iya kuyenza ixhaswe lulwazi esiya kubonelela ngalo.
Ubudlelwane obuphumayo
Le yenye yeempawu zogcino-lwazi olusazisa ukuba ayilulo lonke unxulumano lokugcinwa kwedatha, kodwa kukho ezinye ezisetyenziselwa ukwenza imibuzo eyahlukeneyo.
Olu nxibelelwano lwemibuzo ludume njengobudlelwane obuvelayo, olulungele imibuzo njengoko lubonisa ulwazi ngokungathi yitafile enye.
Obu budlelwane bufunyenweyo bunokumiselwa sithi, abasebenzisi, okanye ngento elula yokuba isiseko sedatha sinobudlelwane. Kolu hlobo lwedatha, lisivumela ukuba senze izithintelo ezahlukeneyo ukuze sikwazi ukunciphisa idatha eyahlukileyo egcinwe kwitafile.
Imimandla
Le yenye yeempawu zesiseko sedatha, esivumela ukuba sichaze isethi yamaxabiso ahlelwe ngeempawu ezifana nawo. I-domain inamandla okuthintela amaxabiso esiwabalulileyo kwimithintelo yobudlelwane obufunyenweyo. Ukuthetha ngemathematika, imimandla zizinto ezenza eli xabiso lingene kolu seti.
Kuhlelo lwesizinda kukho iindidi ezahlukeneyo apho sinokuthiya amagama apheleleyo, imihla, imitya yokubhaliweyo, phakathi kwezinye. I-database yobudlelwane inommandla ngamnye ochonga ngokukodwa, olu manyano lwemimandla luphawulwa ngokumiselwa ziitheyibhile ezahlukeneyo ezaziwa ngokuba sisitshixo esiphambili.
izitshixo eziphambili
Xa sibhekisela kwizitshixo eziphambili, sithetha ngesitshixo esibonakaliswa ngokuqulunqwa kwentsimi enye yetafile. Yeyiphi ekhethiweyo ukufezekisa umfaki-sicelo ngamnye ochaza imbeko nganye eyahlukeneyo eyenza iitafile.
Indlela esilawula ngayo ukuseka obu budlelwane phakathi komntu ngamnye kubo ngokusebenzisa into eyaziwa njengezitshixo zangaphandle okanye zangaphandle.
izitshixo zasemzini
Enye yeempawu zesiseko sedatha yobudlelwane kukukwazi ukunxulumana nezitshixo zangaphandle, ezichongwa bubudlelwane phakathi kweetafile ezimbini.
Omnye umahluko phakathi kwesi sitshixo kunye nesangaphambili kukuba isitshixo esiphambili kufuneka sibe sodwa kwitafile apho zifunyenwe khona. Izitshixo zangaphandle kufuneka zibe zodwa apho ireferensi ikhoyo, hayi apho zifumaneka khona.
iqhosha lesalathiso
Enye yeempawu ezibalaseleyo zogcino-lwazi zizitshixo zesalathiso, ezivela kwisidingo sokufikelela ngokukhawuleza okukhulu kwidatha esiyiphathayo.
Xa sisebenzisa olu hlobo lwesalathiso sinokufumana idatha esiyiphathayo nokuba iirekhodi esiziphetheyo azifumaneki ngokulandelelanayo. Kubalulekile ukuqaphela ukuba ezi zitshixo zesalathiso zisasazwa liqela elinye labantu abaphuhlisa oovimba beenkcukacha esisebenza nabo.
Iinkqubo ezigciniweyo
Le yenye yezinto zokugqibela zesiseko sedatha esinokuthi sikhankanye. Ezi nkcukacha zolwazi zivumela ngamnye wethu ukuba enze inkqubo enekhowudi enokuthi iqhutywe kwaye igcinwe.
Ezi ntlobo zeenkqubo ziqhele ukuqokelela kwaye zinokudibanisa iindlela ezifanayo zokuphumeza ukufakwa kwerekhodi kuzo naziphi na iitheyibhile esizilawulayo.
Ezi ntlobo zeenkqubo zokugcina zisetyenziswa yi-API (i-Application Programmers Interface), ngenxa yokulula kunye nokukhuseleka ukuba nganye yezi nkqubo inikezela.
Ngendlela efanayo, sikushiya ukuba ungene kwividiyo elandelayo apho iimpawu zesiseko sedatha zichazwe ngendlela eguquguqukayo.
https://www.youtube.com/watch?v=lPPv18as9N4
Database
Iidatabase zesinye seziseko zaso nasiphi na isixokelelwano sekhompyuter, oku kungenxa yokuba abadwelisi benkqubo bafuna izixhobo ezahlukeneyo ezibanceda babonelele ngedatha yokuveliswa kweenkqubo ezintsha ngokukhawuleza nangokuthembekileyo.
Ezi nkcukacha zogcino-lwazi zinokuveliswa kwaye zilawulwe yinto eyaziwa ngokuba ziinkqubo zolawulo lwesiseko sedatha, ezi ziinkqubo zesoftware ezikwaziyo ukunxibelelana neenkqubo ezahlukeneyo ukuze sibe nolwazi olwahlukileyo olukhoyo.
Okwangoku iimpawu zesiseko sedatha zilawulwa lubudlelwane. Phakathi kwabaphathi bala vimba beenkcukacha zobudlelwane sifumana:
- db2: Lo mphathi uvumela thina abasebenzisi ukuba sibe neDBMS ephethwe yi-IBM corporate.
- Iseva ye-Microsoft SQL: Lo ngomnye wabaphathi osivumela ukuba siseke iimpawu zedatha epheleleyo. Kuba esi sixhobo seMicrosoft sivumela ukuba sinxulumanise idatha ekhoyo kwilayisensi yeMicrosoft.
- I-MySQL: Iphawulwa ngokuba ngumphathi wesiseko semithombo evulekileyo okwazileyo ukuzibeka njengeyona isetyenziswa kakhulu kwihlabathi liphela.
- I-PostgreSQL: Ukuba sisebenzisa olu hlobo lwabaphathi bedatha sinokuba neetafile zobudlelwane zasimahla ezijolise kwizinto zokuqhelanisa eziphawulwa ngophuhliso oluqhubekayo lomthombo ovulekileyo woluntu.
- Isiseko sedatha yeOracle: le yinkqubo esinokuyifumana kuphela njengesoftware yobunini. Into ekubhekiselwa kuyo kukuba ayisimahla njengeMySQL.
- I-SQLite: lo ngumphathi wedatha wokugqibela esimfumeneyo, eyenziwe lithala leencwadi elipheleleyo leenkqubo ezikwidomeyini yoluntu.
Indlela i-database yobudlelwane isebenza ngayo
Njengoko besesitshilo ngaphambili, oovimba beenkcukacha zobudlelwane ngabo banokuthi ngokuchanekileyo nangokukhawuleza banxulumanise iitafile ezahlukeneyo. Idatha oyifaka kwiitheyibhile iya kwenza i-database yobudlelwane, ngelixa abaphathi bedatha basinika indlela esiza kusebenzisana ngayo, sibhale kwaye sifunde esiya kunika kwisiseko sethu sedatha.
Ukuze senze iimpawu zesiseko sedatha, kufuneka sithathele ingqalelo ukuba ubuncinane enye yale misebenzi ilandelayo kufuneka yenziwe.
Inkcazo yezakhiwo zedathabheyisi
Xa kumiselwa iimpawu zesiseko sedatha, inkcazo yesakhiwo isisiseko ekudalweni kwezi. Ekuqaleni kwenkcazelo yogcino-lwazi lwethu, inkcazo iya kugcinwa ngokuzenzekelayo noko kwaziwa ngokuba yimetadata ukuze kumiselwe oko kwaziwa ngokuba sisichazi-magama sedatha.
Ngokulawula ukuba isigama sethu sichazwe, siya kukwazi ukuchaza idatha nganye eyenza isiseko sethu, esibizwa ngokuba yi-Data Definition Language (DDL).
Inkcazo yamalungelo
Xa sikwazi ukucacisa isigama sethu, kufuneka siqonde ukuba enye yeempawu zogcino-lwazi yinkcazelo yamalungelo olwimi oluxeliweyo. Ukukwazi ukuqonda ukuba iimvume zinganikwa okanye zihoxiswe kwaziwa ngokuba yiDatha yoLawulo lweDatha (DCL) okanye ulwimi olulawulwa yidatha. Esikukhumbulayo ukuba zizigama ezenziwe ngeelwimi ezivela koovimba beenkcukacha ezahlukeneyo.
Inkcazo yeemeko zengqibelelo
Enye into ebalulekileyo ekudalweni kwayo nayiphi na i-database yinkcazo yeemeko zemfezeko eziseka iimfuno ezahlukeneyo ezinabela kwiinkcukacha ezahlukeneyo.
Nganye yale miqathango kufuneka ichazwe ukufezekisa intembeko yesiseko sedatha kwaye ngoko ikwazi ukuqinisekisa ukusebenza kwayo kakuhle.
Inkcazo yeentengiselwano
Xa sidala i-database, kufuneka siqaphele ukuba ukuthengiselana kuluhlu lwemiyalelo eya kuhlala isenziwa ngendlela edibeneyo.
Kuyimfuneko ukuseta ukubuyisela umva kwinkqubo yethu ukuba ube nenketho yokubuyisela i-database kwimeko yayo yokuqala kunye nokufezekisa ukuthengiselana. Oku kuphunyezwa ngokubulela ukuqaliswa kokuhanjiswa kovimba beenkcukacha ezahlukeneyo ukuze bakwazi ukuvelisa ukuqinisekiswa okanye ukuzibophelela kwenkqubo.
Isigama esisebenzisa ezi mpawu zogcino lwedatha yiData Manipulation Language (DML) ethatha inkathalo ukuba imisebenzi ebeka uvimba weenkcukacha emngciphekweni ayibhalwa ngokusisigxina kwaye ivale uqhagamshelo kuvimba wedatha.
Inkcazo yotyelelo
Olu hlobo lwe-database generator luvumela ukuba siseke iimpawu ezithile zogcino-lwazi oluvelisa iitheyibhile zenyani ezahlukeneyo ezinobudlelwane obunengqiqo. Iimbono eziveliswa kwezi theyibhile zinenyani zisivumela ukuba siseke iiseti ezahlukeneyo ezenza iitafile ezintsha.
Xa sichaza ngokuchanekileyo ukutyelela, sinokuhlula iintlobo ezahlukeneyo zokujonga, apho ezona ziqhelekileyo zichazwe ngumbuzo wokukhetha okanye iikholomu.
Izinto ezilungileyo zeempawu zesiseko sedatha yobudlelwane
Ulwimi oluphuhliswa kwiinkcukacha zolwazi lulwimi lwe-SQL (Ulwimi oluQululweyo lwemibuzo) olugxile kwialjebra yobudlelwane. Olu hlobo lwemisebenzi ngaphakathi kwisiseko sedatha sivumela ukuba sibonisane, sihlaziye, sicime okanye senze idatha ezondla ezi tafile zahlukeneyo.
Enye yeempawu zesiseko sedatha yobudlelwane kukuba isinika ngokulula kakhulu xa siphuhlisa imodeli yedatha. Ekubeni isekelwe kwiitafile ezahlukeneyo ezisetyenziswayo kwaye zilawulwa ngokukhawuleza kwezinye iimodeli.
Olu hlobo lwesakhiwo luvumela ukuba sigcine umthengi ohlukeneyo, umthengisi okanye idatha yokunyakaza ngokukhawuleza nangokuchanekileyo, okusivumela ukuba silawule kakuhle ixesha kunye nezixhobo ze-brand.
Olunye uncedo olunikezwa lolu hlobo lwedatha kukuba sibulela kwiifom ze-organic zemodeli kunye nendlela elawula ngayo ukudibanisa, ukuphindaphinda phakathi kwedatha eyahlukileyo esinayo kuye kwancitshiswa kakhulu.
Le mimiselo iye yavumela idatha esondla iitheyibhile ezahlukeneyo ukuba ilungelelaniswe ngokukhululekileyo ngokulula ukuhlela idatha nganye, eyenza lula ukugcinwa ekufuneka sikunike nganye kwezi.
Ngakolunye uhlangothi, ezi mpawu zesiseko sedatha zisivumela ukuba silungelelanise ukuhambelana okuphezulu kwedatha, eya kuveliswa ngenxa yolwazi lwedatha enegalelo ekungqineni kokutya kwiitafile.
Ngelixa ulungisa idatha nganye ujolise kwiiseti ezenziwe ngaphakathi kweetafile. Oku kusivumela ukuba siqhagamshele ngokupheleleyo iqumrhu ngalinye elixhasa imixholo eyahlukeneyo.
Okokugqibela, phakathi kweenzuzo zeempawu zesiseko sedatha esinengqiqo lulwimi lwemibuzo ehambelanayo enkosi ekudityanisweni kolwimi olunikezelwa yi-SQL kumbulelo wokumisela umgangatho we-ISO kunye ne-IEC.
Ukungalungi koovimba beenkcukacha zobudlelwane
Emva kokumisela iimeko apho oovimba beenkcukacha besisiseko kunye nendlela ezi ntlobo zeetheyibhile ziphathwa ngayo ngokupheleleyo. Sifumana izinto ezingalunganga okanye eziphazamisayo ezivela xa sisebenza nabo, esinokuzichaza ngeendlela ezahlukeneyo.
Enye yeengxaki ezivela kwezi mpawu zesiseko sedatha yinkcazo yazo. Iitheyibhile zobudlelwane azisoloko zisivumela ukuba sidibanise iindidi ezahlukeneyo zedatha okanye ifomathi yeetafile ezine-dimensional, nangona siye sakwazi ukuzidibanisa.
Ngendlela efanayo, idatha engabonakaliyo okanye engacwangciswanga kakuhle ivela ngendlela apho izicelo zefomathi ye-multimedia ayivumeli ukubonakaliswa kweemodeli zobudlelwane.
Kwelinye icala, oovimba beenkcukacha abanxulumeneyo abaphenduli ngokufanelekileyo okanye ngokufanelekileyo kwiinkqubo ezingezizo ezobume. Yintoni esithintelayo ekuphumezeni iikhonsepthi ezahlukeneyo ezisivumela ukuba sizuze ilifa kwiipropati ezivela kumaziko aphezulu.
Enye yezinto ezingeloncedo olu hlobo lwesiseko sedatha esinxibelelana nazo kukwahlulwa kwedatha nganye. Ukususela ekuqaleni kwezi thebhile, iseti esondla ubudlelwane obahlukeneyo sifuna ukugcina ulwazi kwiitheyibhile ezahlukeneyo okanye into esiyaziyo njengesiqhelo, esivumela ukuba sifikelele ngokukhawuleza into esiyaziyo njengokwahlula. Olu yilo luzalwa kwimibuzo egubungela itafile nganye, ebonakalisa kakubi inani lamacandelo adalwe.
Ekugqibeleni, abadwelisi beprogram abahlukeneyo baye bahlula ukuba iimpawu zesiseko sedatha ebudlelwaneni zibi kakhulu ukuba zibe nokusebenza okusemgangathweni xa kuthelekiswa nedatha efana ne-NoSQL. Ekubeni idatha yobudlelwane ivumela ukuba sibeke amanani afunekayo ukuvavanya ukuhambelana kwedatha, ngelixa ii-database ze-NoSQL zisebenza ngokufanelekileyo ngokubonga ukuba isantya sokubhala ukuthengiselana kuya kwanda ngokulinganayo.