Kuisa Dhiyabhorosi muFomu Yechipiri Yakarongeka
Mumwedzi wapfuura, takatarisa zvinhu zvakasiyana-siyana zvekusimudzira tafura ye database. Chokutanga, takakurukura nheyo dzemitemo yekusimudzira. Nguva yekupedzisira, takaongorora zvinhu zvinodiwa zvakagadzirirwa neyekutanga maitiro (1NF). Iye zvino, ngatirambei tichifamba rwendo rwedu uye tivhare mitemo yechipiri yechimiro chechipiri (2NF).
Yeuka zvinowanzodiwa zve 2NF:
- Bvisa zvinyorwa zvemashoko zvinoshanda kumitsara yakawanda yefurafura uye uzviise mumatafura akasiyana.
- Ita hukama pakati pematafura aya matsva uye avo vanofanotanga kuburikidza nokushandiswa kwezvikwere zvekunze.
Mitemo iyi inogona kuiswa muchidimbu mumashoko akareruka: 2NF inoedza kuderedza kuwandisa kwezvinyorwa zviri mutafura nekuibudisa, kuiisa mumatafura matsva (s) nekuumba ukama pakati pematafura aya.
Ngatitarisei muenzaniso. Fungidzira imwe nzvimbo yepaIndaneti inochengetedza ruzivo rwevatengi mu database. Vanogona kuva nefurafura imwe chete inonzi Vatengi nezvinhu zvinotevera:
- CustNum
- Zita rokutanga
- Zita rokupedzisira
- Address
- Guta
- State
- ZIP
Kuongorora kwenguva pfupi patafura iyi kunoratidza huwandu hwemashoko akawandisa. Tiri kuchengetedza "Sea Cliff, NY 11579" uye "Miami, FL 33157" inowanikwa kaviri. Iye zvino, izvo zvingasaita sezvakawandisa-kuwedzerwa kuchengetedza mumuenzaniso wedu wakajeka, asi fungidzira nzvimbo yakasara kana taive nezviuru zvemiromo patafura yedu. Kuwedzerwa, kana iyo ZIP code yeGungwa Cliff yaifanira kuchinja, tinoda kuchinja ikoko munzvimbo dzakawanda mu database.
Mune 2NF-inoenderana nemasangano epa database, ino ruzivo rwekuregererwa inobviswa uye yakachengetwa mune imwe tefura yakasiyana. Tafura yedu mutsva (ngatiidane iyo ZIPs) inogona kuva neminda inotevera:
- ZIP
- Guta
- State
Kana tichida kuva nehupamhi-shingaira, tinogona kuzadza tafura iyi zvisati zvaitika - positi yehofisi inopa bhuku rezvesiti dzakachengetedzwa dze ZIP pamwe nehukama hwavo hwehurumende. Zvechokwadi, wakambosangana nemamiriro ezvinhu apo iyi yepa database yakashandiswa. Mumwe munhu anotora urongwa angave akakukumbira kuti utore Code yako yekutanga ndokuzoziva guta racho nehurumende yauri kudana kubva. Urwu urongwa hwegadziriro hunoderedza kukanganisa kwevashandi uye hunowedzera kubudirira.
Iye zvino zvatakabvisa dhipatimendi yedhipatimendi kubva kuTerenda yeVatengi, takagutsa murairo wekutanga wechimiro chechipiri. Tichiri kuda kushandisa kiyi yekune imwe nyika kuti tisunge matata maviri pamwe chete. Tichatshandisa ZIP code (iyoyi yekutanga inobva paZIP table) kuti uite ukama uhwu. Heino vatengi vedu vatengi tafura:
- CustNum
- Zita rokutanga
- Zita rokupedzisira
- Address
- ZIP
Isu tave takaderedza huwandu hwehuwandu hwemashoko akachengetwa mud database uye sangano redu riri muchipiri chimiro chakanaka!
Kana iwe uchida kuongorora kuti database yako inowirirwa, tsvaga zvimwe zvinyorwa zvedu munyaya dzino:
- Dhesi reNormalization Basics
- Kuisa Database yako muFomu Yokutanga Yakarongeka
- Kuisa Database yako muFomu Yechipiri Yakarongeka
- Kuisa Database yako muTormal Normal Form