Zokhudzana ndi zida zapamwamba ndi nkhani yomwe nthawi zambiri imasokoneza onse ophunzira ndi ofufuza zapamwamba. Mwamwayi, sizili zovuta ndipo zingathe kufotokozedwa bwino pogwiritsa ntchito zitsanzo zingapo. M'nkhaniyi, timayang'ana mitundu yodziwika bwino yodalirana.
Kusamalidwa Kwadongosolo / Ntchito Zogwira Ntchito
Kudalira kumapezeka mu deta pamene nkhani yosungidwa m'masamba omwewo amadziŵitsa bwino zinthu zina zomwe zili mu tebulo lomwelo. Mungathe kufotokozeranso izi ngati chiyanjano pamene kudziwa phindu la chinthu chimodzi (kapena chikhalidwe cha zikhumbo) ndikwanira kuti ndikuuzeni kufunika kwa chikhumbo china (kapena chikhalidwe cha makhalidwe) mu tebulo lomwelo.
Kunena kuti pali kudalira pakati pa zikhumbo patebulo ndi chimodzimodzi kunena kuti pali kudalira kogwirizana pakati pa makhalidwe amenewo. Ngati pali kudalira m'databata kotero kuti chikhalidwe B chimadalira chikhumbo A, mukhoza kulemba izi monga "A -> B".
Mwachitsanzo, Mu tebulo akuphatikiza maofesi omwe amagwira ntchito kuphatikizapo Social Security Number (SSN) ndi dzina, zikhoza kunenedwa kuti dzina limadalira SSN (kapena SSN -> dzina) chifukwa dzina la ogwira ntchito likhoza kukhazikitsidwa mwachindunji ku SSN yawo. Komabe, mawu otsutsa (dzina -> SSN) si oona chifukwa antchito angapo akhoza kukhala ndi dzina lomwelo koma SSN zosiyana.
Zochepa Zogwira Ntchito Zochepa
Kudalira kokha kopanda ntchito kumachitika pamene mumalongosola kudalira kogwira mtima kwa chikhumbo pa zikopa zamagulu zomwe zimaphatikizapo chikhalidwe choyambirira. Mwachitsanzo, "{A, B} -> B" ndi kudalira kochepa, monga "{dzina, SSN} -> SSN". Kugonjera kotereku kumatchedwa kuchepa chifukwa kungatengedwe kuchokera kumaganizo. Zili zoonekeratu kuti ngati mutadziwa kale kufunika kwa B, ndiye kuti ubwino wa B ukhoza kukhala wotsimikizirika ndi chidziwitso chimenecho.
Kugwira Ntchito Kwathunthu
Kudalira kwathunthu kwa ntchito kumachitika pamene mwakwaniritsa kale zofunikira kuti mukhale wogwira ntchito ndikukhazikitsidwa kwa zizindikiro pambali ya kumanzere kwa mawu ogwira ntchito ogwira ntchito sangathe kuchepetsedwa. Mwachitsanzo, "{SSN, zaka} -> dzina" ndizodalira, koma sizomwe zimadalira ntchito chifukwa mutha kuchotsa zaka kuchokera kumanzere kwa mawu popanda kukhudza ubwenzi wodalira.
Kusintha Kwambiri
Kudalira kusinthika kumachitika ngati pali ubale wosalunjika umene umayambitsa kudalira. Mwachitsanzo, "A -> C" ndidali ndikutembenuka mtima pamene ziri zoona chifukwa zonse "A -> B" ndi "B -> C" ndizoona.
Zomwe Zimadalira Kwambiri
Kudalira kwakukulu komwe kumachitika pamene kukhalapo kwa mzere umodzi kapena kuposera patebulo kumatanthauza kupezeka kwa mzere umodzi kapena mizere mu tebulo lomwelo. Mwachitsanzo, taganizirani kampani ya galimoto yomwe imapanga mitundu yambiri ya galimoto, koma nthawi zonse imapanga mitundu yonse yofiira ndi ya buluu. Ngati muli ndi tebulo yomwe ili ndi dzina lachitsanzo, mtundu ndi chaka cha galimoto iliyonse kampani ikupanga, pali kudalira kwakukulu mu tebulo. Ngati pali mzere wa dzina linalake ndi chaka mu buluu, payenera kukhala mzere womwewo wofanana ndi mtundu wofiira wa galimoto yomweyo.
Kufunika Kokhala ndi Zomwe Zimadalira
Zomwe zimagwirizanitsa zida zapamwamba ndizofunikira kumvetsetsa chifukwa zimapanga zofunikira zomwe zimagwiritsidwa ntchito pazinthu zamakono . Mwachitsanzo:
- Kuti patebulo likhale lachiwiri (2NF) , payenera kukhala palibe chifukwa cha chikhalidwe chosakhala choyambirira mu tebulo chomwe chimagwira ntchito pamagulu a chinsinsi cha olemba .
- Kuti patebulo likhale lachitatu lachibadwa (3NF) , chikhalidwe chilichonse chosakhala choyambirira chiyenera kukhala chodalira chosagwira ntchito pachinsinsi chilichonse cha olembapo.
- Kuti pakhale tebulo kuti likhale mu Boyce-Codd Fomu Yachibadwa (BCNF) , kugwiritsidwa ntchito kulikonse (kupatulapo kudalira kwakukulu) kumayenera kukhala pamwamba.
- Kuti patebulo likhale lachinayi lachibadwa (4NF) , siliyenera kukhala ndi zidindo zambiri.