Eli gamaziso lugcina imiqathango yolwazi kunye nolwazi olusetyenziswa kuzo zonke iindidi zolwazi. Akubandakanyi imigaqo ethile kwiinkqubo ezithile okanye iinkcukacha.
ACID
Imodeli ye- ACID yolondolozo lweenkcukacha ikhuthaza ubutyebi bwedatha ngokusebenzisa i- atomicity , ukuvumelana , ukuhlukaniswa kunye nokuzinza:
- I-Atomicity: nganye Intetho yokulandelelana kufuneka ilandele yonke into engekho-nantoni-nto, nto leyo ithetha ukuba ukuba nayiphi na inxalenye yentengiso ayiphumelelanga, yonke into eyenziwa ngayo ihluleka.
- Ukubambisana : Ukuthengiswa kwedatha nganye kufuneka kulandele yonke imithetho echaziweyo yedata; nawuphi na umthengi onokuphulaphula le mithetho akavumelekanga.
- Ukuqhawulwa kweeNkcukacha : Ukuthengiswa kwedatha nganye kuya kwenziwa ngokuzimeleyo kwanoma yimuphi umthengi. Ngokomzekelo, ukuba iintengiso ezininzi zingeniswa kwangoku, i-database iya kuthintela ukuphazamiseka phakathi kwabo.
- Ukuzinyameka : Ukuthengwa kwedatha nganye kuya kubakho ngokusisigxina kuyo nayiphi na ukungaphumeleli kwedatha, ngokusebenzisa i-backups okanye ezinye iindlela.
Isixhobo
Isalathisi sesiseko sedatha yinkalo yeziko leenkcukacha. Ukubeka nje, impawu yikholam etafileni yedatha, eyaziwayo njengeziko.
Ukuqinisekiswa
IiNgcaciso zisebenzisa ukuqinisekiswa ukuqinisekisa ukuba abasebenzisi abagunyazisiweyo banokufikelela kwiziko leenkcukacha okanye iinkalo ezithile zeenkcukacha. Ngokomzekelo, abalawuli banokugunyazwa ukufaka okanye ukuhlela idatha, ngelixa abasebenzi abaqhelekileyo banako ukujonga kuphela idatha. Ukuqinisekiswa kuphunyezwa ngamagama abasebenzisi kunye namaphasiwedi.
BASE Model
Imodeli yeBASE iye yaphuhliswa njengenye indlela kumzekelo we-ACID ukulungiselela iimfuno ze-SQL yolwazi apho idatha ayilwanga ngendlela efanayo efunwa ziinkcukacha zolwazi. Iingqinisiso zayo eziphambili zi-Basic Availability, State Soft, kunye ne-Eventual Consistency:
- Ukufumaneka ngokusisiseko : Isiseko sedatha siyafumaneka kwaye sisebenza, sixhaswe ngamanye amaxesha ngokuphindaphinda kwedatha kusasazwa kumaseva athile.
- I-State soft : Ukulwa nomzekelo we-ACID wokuzimelela ngokuthe ngqo, le tenet ithi idatha ayisoloko ihlale ihambelana kwaye ukuba nayiphi na into eqhotyoshelweyo ixanduva lomgcini-nkcukacha ngamnye okanye umqhubi.
- Ukubambisana ngokuqhubekayo : Kwinqanaba elingasichazwanga, i-future point, i-database iya kufezekiswa.
Imiqobo
Umqobo wesiseko yiseti yemigaqo echaza idatha echanekileyo. Zininzi iintlobo zeengxaki. Iingxaki eziphambili zi:
- Imithintelo eyingqayizivele : Intsimi mayibe nexabiso elithile kwitafile.
- HLOLA imithintelo : Insimu inokuthi iqulethe kuphela iindidi zeenkcukacha ezithile kunye neemeko ezithile ezivumelekileyo.
- IINTSHOLONGO ZEMISEBENZI : Intsimi iya kuba nexabiso elingagqibekanga ukuba lingenayo ixabiso elikhoyo; oku kususa ixabiso le-NULL.
- IINGXELO ZEZIKOLO ZIKHARITYHULAM : Inqobo ephambili kufuneka ibe yodwa.
- IZINTO EZIKHULULEKILEYO : Inkcenkca yangaphandle kufuneka ihambelane nencoko ephambili ekhoyo kwenye ietafile.
Inkqubo yoLawulo lweDatabase (iDBMS)
I-DBMS isofthiwe esilawula yonke imiba yokusebenza kunye nedatha, ukusuka ekugcineni nasekugcineni idatha ukuze kuqinisekiswe imigaqo yokuthembeka kwemigaqo, ukubonelela ngefom zokungena kwedatha nokuphathwa. Inkqubo yoLawulo lweDatabase yoLwazi (RDBMS) isebenzisa imodeli yobudlelwane kunye nobudlelwane phakathi kwabo.
IQumrhu
Iqumrhu liphela nje itafile kwisiseko sedatha. Kucaciswa kusetyenziswa iSikripthi soBudlelwane boBambiswano, oluhlobo lomzobo obonisa ubudlelwane phakathi kweetafile zeenkcukacha.
Ukuxhomekeka kokuSebenzayo
Inkqubo yokuxhomekeka ekuxhomekeke kumsebenzi inceda ukuqinisekisa ukuqinisekiswa kwedatha, kwaye ikhona xa enye impawu ichaza ixabiso lenye, ichazwa njenge- A -> B elithetha ukuba ixabiso le-A lixhomekeke kwixabiso leB, okanye ukuba iB "ixhomekeka ngokusemthethweni" kwi-A Ngokomzekelo, itafile eyunivesithi equka iirekhodi zabo bonke abafundi banokuba nokuxhomekeka okusebenzayo phakathi kwe-ID yomfundi kunye negama lomfundi, oko kukuthi i-ID yesazisi ekhethekileyo iya kugqiba ixabiso legama.
Index
Isalathisi sisakhiwo senkcukacha esinceda imibuzo yokukhawuleza yeenkcukacha zeedasethi ezinkulu. Abaphuhlisi beenkcukacha basebenzise inkcazo kwiikholomu ezithile kwietafile. Isalathisi sithatha ixabiso lekholomu kodwa zibonisa nje iinkcukacha kwi-data kuyo yonke itafile, kwaye iyakusesha ngokuchanekileyo kwaye ngokukhawuleza.
Ngundoqo
Isibalulekileyo yintsimi yedatha enenjongo yokuzikhethela ngokukodwa irekhodi. Uncedo lweekhonkco lugxininisa ukuthembeka kwenkcukacha kwaye uphephe ukuphindaphinda. Iintlobo eziphambili zitshixo ezisetyenzisiweyo kwiziko leenkcukacha zitshixo zefowuni, izitshixo zangundoqo zezixhobo zangaphandle.
- Izitshixo zokukhetha : Iqoqo lamakholomu anokukhetha ngokukodwa irekhodi kunye nalapho ikhetho lokuqala likhethwa khona.
- Izitshixo zaseprayimari : Isitshixo esikhethiweyo ukuchonga irekhodi kwitafile. Esi sitshixo asikwazi ukuba yi-NULL.
- Iitshixo zangaphandle : Iqhosha elidibanisa irekhodi kwirekhodi kwelinye itafile. Ikhefu langaphandle letafile kufuneka libe khona njengeyona nto iphambili yenye itafile.
Ukumisa
Ukuqhelanisa isiseko sedatha kukuyila iitheyibhile zayo (ubudlelwane) kunye neentsika (iimpawu) ngendlela yokuqinisekisa ukuthembeka kwenkcukacha kunye nokuphepha ukuphinda. Amanqanaba aphambili oqhelekileyo yiFomu eQalayo eqhelekileyo (1NF), Ifom yesiBini yesiQhelo (2NF), ifom yeSiqhelo elinesithathu (3NF) kunye neFomily-Codd Fom Form (BCNF).
I-NoSQL
I-NoSQL iyimodeli yedatha ephuhlisiwe ukuphendula kwisidingo sokugcina idatha engaqinisekanga njengee-imeyile, izithuba zoononophelo zoluntu, ividiyo okanye imifanekiso. Esikhundleni sokusebenzisa i-SQL kunye ne-ACID imodeli eqinileyo ukuqinisekisa ukuthembeka kwedatha, i-NoSQL ilandela imodeli engqongqo ye-BASE. Isicwangciso se-NoSQL sedata ayisebenzisi iitafile ukugcina idatha; kunoko, isenokusebenzisa i-key / value design okanye igrafu.
Null
Ixabiso le- NULL lihlala lididekile ukuba lithetha "akukho" okanye i-zero; nangona kunjalo, oko kuthetha "abangaziwa." Ukuba insimu inenani le-NULL, ngumnini-nendawo yexabiso elingaziwa. ULwimi oluCwangcisiweyo lweSicelo (SQL) lisebenzisa i-NULL NABASEBENZISI be-NULL ukuvavanya iimpawu ezingenanto.
Umbuzo
Umbuzo wesiseko sendlela abasebenzisi abasebenzisana ngayo nedatha. Ngokuqhelekileyo kubhalwa kwi-SQL kwaye ingaba ngumbuzo wokukhetha okanye umbuzo wesenzo . Isicelo seenkcukacha zokukhetha sicelo esivela kwisiseko sedatha; utshintsho lombuzo, uhlaziyo okanye ungeze idatha. Ezinye iinkcukacha zibonelela ngeefom ezifihla i-semantics yombuzo, ukuvumela abasebenzisi ukuba bacele ulwazi ngokulula ngaphandle kokuba baqonde iSQL.
Schema
Isicwangciso seenkcukacha zolwazi luyilo lweetables, iikholomu, ubudlelwane kunye neengxaki ezenza i database. I-Schemas idla ngokucacileyo isebenzisa isitatimende SQL CREATE.
Inkqubo egcinwe
Inkqubo egcinwe ngumbuzo oqulunqwe ngaphambili, okanye isitatimende se-SQL esinokubelwa kuzo iinkqubo ezininzi kunye nabasebenzisi kwiShedisti yoLawulo lweDatabase. Iinkqubo ezigcinwe ziphucula ukusebenza kakuhle, uncedo ukunyanzelisa intembeko yedatha nokuphuhlisa imveliso.
ULwimi oluCwangcisiweyo loLwimi
ULwimi oluCwangcisiweyo lweSicelo , okanye i-SQL, ulwimi oluqhelekileyo olusetyenziswayo ukufikelela kwiinkcukacha ezivela kwisiseko sedatha. ULwimi lokuLawulwa kweData (iDML) luqulethe i-subset yemiyalelo ye-SQL esetyenziswe rhoqo kwaye iquka ukukhethwa, GCINISWA, PHEKA KUNYE KUNYE.
Trigger
I-trigger yinkqubo egcinwe ukwenza ukunikezelwa kwesiganeko esithile, ngokuqhelekileyo utshintsho kwidata yetafile. Ngokomzekelo, i-trigger ingahle yenzelwe ukubhala kwi-log, ukuqokelela inani okanye ukubala ixabiso.
Jonga
Umboniso wesiseko sedatha ehlongozwayo yedatha eboniswe kumsebenzisi wokugqibela ukwenzela ukufihla ubunzima beenkcukacha kunye nokuhlaziywa kwamava omsebenzisi. Imbono inokudibanisa idatha kwitafile ezimbini okanye ngaphezulu kwaye iqulethe i-subset yolwazi.