Ukulinganisela i-Database yakho
Uma usebenze ngolwazi oluthile okwesikhashana, kungenzeka ukuthi uzwile ukujwayela kwegama. Mhlawumbe othile wakubuza ukuthi "Ingabe lelo datha lijwayelekile?" noma "Ingabe lokho kuyi- BCNF ?" Ukumisa ngokuvamile kuvunyelwe eceleni njengendlela yokunethezeka okuwukuphela kwezifundiswa ezinesikhathi. Kodwa-ke, ukwazi izimiso zokujwayelekile nokuzifaka emisebenzini yakho yokwenza imisebenzi yezinsuku zonke akuzona zonke izinto eziyinkimbinkimbi futhi kungathuthukisa kakhulu ukusebenza kweDBMS yakho.
Kulesi sihloko, sizokwethula umqondo wokujwayelekile futhi sibheke amafomu avamile kakhulu.
Kuyini Normalization?
Ukujwayelekile kuyinkqubo yokuhlela idatha ngendlela egciniwe yedatha. Kunemigomo emibili yenqubo yokujwayelekile: ukuqeda idatha ephindaphindiwe (isibonelo, ukugcina idatha efanayo kumathebula angaphezu kweyodwa) nokuqinisekisa ukuxhomeka kwedatha kunengqondo (ukugcina imininingwane ehambisanayo etafuleni kuphela). Zombili lezi ziyizinhloso ezifanele njengoba zinciphisa inani lesikhala i-database idla futhi iqinisekise ukuthi idatha igcinwe ngokulinganayo.
Amafomu ajwayelekile
Umphakathi wedatha uthuthukise uchungechunge lwemikhombandlela yokuqinisekisa ukuthi imininingwane yolwazi iyajwayelekile. Lezi zibizwa ngokuthi yizifomu ezijwayelekile futhi zibalwa kusukela kwesinye (ifomu eliphansi kakhulu lokujwayelekile, elibhekwa njengefomu elivamile noma 1NF) ngokusebenzisa amahlanu (ifomu lesihlanu evamile noma 5NF). Ezenzweni zokusebenza, uzovame ukubona i-1NF, i-2NF, ne-3NF kanye ne-4NF ngezikhathi ezithile. Ifomu lesihlanu evamile alitholakali kakhulu futhi ngeke lixoxwe kule ngxenye.
Ngaphambi kokuba siqale ingxoxo yethu ngamafomu avamile, kubalulekile ukukhomba ukuthi ziyiziqondiso nemihlahlandlela kuphela. Ngezinye izikhathi, kuyadingeka ukuba usuke kubo ukuze uhlangabezane nezidingo zebhizinisi ezisebenzayo. Kodwa-ke, uma ukuhlukahluka kwenzeka, kubaluleke kakhulu ukuhlola noma yikuphi ukulinganisa okungenzeka babe nakho ohlelweni lwakho kanye ne-akhawunti ngokungahambisani okungenzeka. Lokho kusho, ake sihlole amafomu avamile.
Ifomu Lokuqala Elijwayelekile (i-1NF)
Ifomu lokuqala evamile (1NF) libeka imithetho eyisisekelo kakhulu yedatha ehleliwe:
- Khipha amakholomu okuphinda avela kuthebula elifanayo.
- Dala amatafula ahlukene eqenjini ngalinye lemininingwane ehlobene bese uthola irowu ngalinye ngekholomu ehlukile noma iqoqo lamakholomu ( ukhiye oyinhloko ).
Ifomu lesibili elijwayelekile (2NF)
Ifomu lesibili elijwayelekile (2NF) libuye libheke nomqondo wokususa idatha ephindaphindiwe :
- Hlanganisa zonke izidingo zefomu elivamile elivamile.
- Susa ama-subset yedatha asebenza kumigqa eminingi etafuleni bese uwabeka ematafuleni ahlukene.
- Dala ubudlelwane phakathi kwalawa macwecwe amasha kanye nabandulela kwabo ngokusebenzisa ukusetshenziswa okhiye bangaphandle .
Ifomu Lesithathu Elijwayelekile (3NF)
Ifomu lesithathu evamile (3NF) liya phambili elilodwa elikhulu:
- Hlanganisa zonke izidingo zefomu lesibili evamile.
- Susa amakholomu angaxhomeki kukhiye oyinhloko.
Ifomu le-Boyce-Codd elijwayelekile (i-BCNF noma i-3.5NF)
Ifomu le-Boyce-Codd Normal, elibizwa nangokuthi "ifomu elijwayelekile" nelingu "3.5" elijwayelekile, linezela okunye okudingekayo:
- Hlanganisa zonke izidingo zefomu lesithathu evamile.
- Wonke ama-determinant kufanele abe ukhiye wokuzikhethela.
Ifomu Lesine Elivamile (4NF)
Ekugcineni, ifomu lesine elijwayelekile (4NF) linesidingo esisodwa esisodwa:
- Hlanganisa zonke izidingo zefomu lesithathu evamile.
- Ubuhlobo bukhona ku-4NF uma kungenakho ukuxhomekeka okubaluleka okuningi .
Khumbula, lezi ziqondiso zokujwayelekile zihlanganisa. Ukuze i-database ibe ku-2NF, kufanele kuqala igcwalise yonke imigomo ye-database ye-1NF.
Ngifanele Ngiyiqede?
Ngenkathi i-normalization ye-database ingumqondo omuhle, akuyona into edingekayo. Eqinisweni, kunezinye izimo lapho ukwephula ngamabomu imithetho yokujwayelekile kuyindlela enhle. Ukuze uthole okwengeziwe ngalesi sihloko, funda Kufanele Ngifinyelele I-Database Yami Ejwayelekile?
Uma ungathanda ukuqinisekisa ukuthi i-database yakho ijwayelekile, qala ngokufunda ukuthi ungabeka kanjani imininingwane yakho kuFomu Elijwayelekile Lokuqala .