Nyob rau hauv cov txheej txheem normalization ib nrab kev vam meej txhais tau tias?

Cov txheej txheem:

Nyob rau hauv cov txheej txheem normalization ib nrab kev vam meej txhais tau tias?
Nyob rau hauv cov txheej txheem normalization ib nrab kev vam meej txhais tau tias?

Video: Nyob rau hauv cov txheej txheem normalization ib nrab kev vam meej txhais tau tias?

Video: Nyob rau hauv cov txheej txheem normalization ib nrab kev vam meej txhais tau tias?
Video: cov txheej txheem ntawm lub rooj me thaum tsaus ntuj 2024, Kaum ib hlis
Anonim

Ib nrab Dependency tshwm sim thaum tus yam ntxwv tsis yog thawj tus cwj pwm ua haujlwm nyob ntawm ib feem ntawm tus neeg sib tw tus yuam sij. Daim Ntawv 2nd Ib txwm (2NF) tshem tawm Ib Feem Kev Cia Siab.

Dab tsi yog qhov kev vam khom ib nrab?

Ib nrab Dependency yog a daim ntawv ntawm Kev Ua Haujlwm Kev vam meej uas tuav ntawm cov yam ntxwv. … Piv txwv li, nyob rau hauv ib tug functional dependency PQ → R, yog P ib leeg los yog Q ib leeg muaj peev xwm cim R, ces qhov no yog hais tias yog ib feem Functional Dependency.

Dab tsi yog qhov normalization kev vam khom?

Ib qho kev ua haujlwm puv ntoob yog xeev ntawm database normalization uas sib npaug rau tus qauv normalization ntawm Thib Ob Hom Ntawv (2NF). Nyob rau hauv luv luv, qhov no txhais tau hais tias nws ua tau raws li qhov yuav tsum tau ntawm First Normal Form (1NF), thiab tag nrho cov yam ntxwv tsis tseem ceeb yog tag nrho functionally nyob ntawm tus yuam sij tseem ceeb.

Dab tsi yog tag nrho thiab ib nrab kev vam khom?

Nyob rau hauv kev ua haujlwm puv ntoob, tsis yog tus cwj pwm tseem ceeb yog ua haujlwm nyob ntawm qhov tus neeg sib tw tus yuam sij. Hauv ib feem ntawm qhov kev vam khom, tsis yog tus cwj pwm tseem ceeb yog ua haujlwm nyob ntawm ib feem ntawm tus neeg sib tw tus yuam sij. … Nyob rau hauv ib feem ntawm kev vam khom, yog tias peb tshem tawm ib qho cwj pwm ntawm X, ces qhov kev vam khom tseem yuav muaj nyob.

Qhov kev vam khom twg yog siv rau hauv normalization?

Ntau Hom Kev Ua Haujlwm Zoo Tshaj Plaws uas siv rau hauv cov txheej txheem Normalization yog: Tag Nrho Kev Cia Siab . Partial Dependency . Txoj kev vam meej.

Pom zoo:

Nyob rau hauv cov txheej txheem nitriding cov nh3 roj tau qhia ntawm?

Nyob rau hauv cov txheej txheem nitriding cov nh3 roj tau qhia ntawm?

diffused rau hauv steel2). Txij li thaum ob qho kev cuam tshuam saum toj no tshwm sim ib txhij hauv furnace, NH3 tau qhia tas li nyob rau hauv lub qhov cub kom cov cua nitriding uas muaj NH3 tswj kom muab nitrogen rau cov hlau . Cov roj twg siv rau hauv cov txheej txheem nitriding?

Cov txheej txheem twg yog txheej txheem gradational?

Cov txheej txheem twg yog txheej txheem gradational?

Gradational processes Weathering=breakdown of material in place Gradation=leveling of land degradation (erosion)=tshem tawm highs transport=txav ntawm cov khoom aggradation (deposition)=filling in lows Tectonic txheej txheem tsim los ntawm roughen lub ntiaj teb Gradational rog theem tawm highs thiab sau nyob rau hauv lows … Qhov twg ntawm cov txheej txheem hauv qab no yog cov txheej txheem gradational?

Cov txheej txheem neoplastic puas txhais tau tias mob qog noj ntshav?

Cov txheej txheem neoplastic puas txhais tau tias mob qog noj ntshav?

Ib qho txawv txav ntawm cov ntaub so ntswg uas tsim thaum cov hlwb loj hlob thiab faib ntau tshaj qhov lawv yuav tsum tau lossis tsis tuag thaum lawv tsim nyog. Neoplasms tej zaum yuav yog benign (tsis yog mob qog noj ntshav) los yog malignant (cancer).

Nyob rau hauv tus txheej txheem desalination twg ntawm cov hauv qab no yog tshem tawm ntawm dej?

Nyob rau hauv tus txheej txheem desalination twg ntawm cov hauv qab no yog tshem tawm ntawm dej?

Desalination yog ib txheej txheem uas tshem tawm ntsev ntau dhau thiab lwm yam minerals tawm ntawm dej. Nyob rau hauv feem ntau cov txheej txheem desalination, pub dej yog kho thiab ob kwj dej yog tsim: kho cov dej tshiab uas muaj tsawg concentrations ntawm ntsev thiab minerals .

Nyob rau hauv cov txheej txheem huab cua ntawm kev tso tawm kev tawg?

Nyob rau hauv cov txheej txheem huab cua ntawm kev tso tawm kev tawg?

Definition: kev nthuav tawm ntawm cov pob zeb tawg nyob ze ntawm qhov chaw ntawm pob zebvim kev nthuav dav ntsig txog kev tso tawm ntawm kev kaw siab thaum lub pob zeb faus tob heev tsis muaj ru tsev. Fractures feem ntau propagate raws qhov chaw nyob ze thiab subparallel rau saum npoo ntawm outcrop .