2024 Tus sau: Elizabeth Oswald | [email protected]. Kawg hloov kho: 2024-01-13 00:07
Raws li Kimball: Cov qauv Dimensional sib xyaw ua ke cov qauv rooj thiab cov qauv tsis zoo. Cov rooj loj ntawm cov lus piav qhia yog qhov tsis zoo nrog cov ncauj lus kom ntxaws thiab hierarchical dov-up cwj pwm hauv tib lub rooj. Lub caij no, cov lus tseeb nrog cov ntsuas kev ua tau zoo yog feem ntau normalized.
Puas yog lub rooj qhov tseeb normalized?
Cov lus tseeb yog qhov qub tag nrho kom tau txais cov ntaub ntawv xov xwm hais txog kev lag luam (txhua cov ntaub ntawv hauv cov lus tseeb), koj yuav tsum koom nrog cov lus tseeb nrog lub rooj dimension. Ib txhia hais tias cov lus tseeb nyob rau hauv cov qauv denormalized vim nws yuav muaj cov yuam sij txawv teb chaws.
Yuav ua li cas cov ntaub ntawv khaws cia hauv cov lus tseeb?
Lub rooj muag khoom tseeb cov ntaub ntawv ntau rau kev tshuaj ntsuamthiab feem ntau denormalized. Lub rooj qhov tseeb ua haujlwm nrog cov rooj loj. Lub rooj qhov tseeb tuav cov ntaub ntawv los txheeb xyuas, thiab lub rooj ntsuas qhov ntev khaws cov ntaub ntawv hais txog txoj hauv kev uas cov ntaub ntawv hauv cov lus tseeb tuaj yeem txheeb xyuas.
Dab tsi yog qhov normalized thiab denormalized ntxhuav?
Nyob rau hauv normalization, Cov ntaub ntawv uas tsis yog redundancy thiab sib xws tau muab khaws cia rau hauv cov schema. Hauv kev denormalization, cov ntaub ntawv tau ua ke los ua cov lus nug sai sai. … Hauv normalization, Cov ntaub ntawv redundancy thiab inconsistency raug txo. Hauv denormalization, redundancy yog ntxiv rau kev ua tiav ntawm cov lus nug.
Vim li cas cov lus tseeb yog daim ntawv ib txwm?
Qhov tseeb lub rooj muaj qhov Index yuam sij ntawm qhov loj me / saib cov ntxhuav thiab ntsuas. yog li thaum twg peb muaj cov yuam sij hauv lub rooj. uas nws tus kheej txhais tau tias lub rooj yog nyob rau hauv ib txwm daim ntawv.
Pom zoo:
Puas yog daim ntawv cog lus tsis muaj tseeb ib yam li cov ntawv cog lus tsis muaj lawm?
Daim ntawv cog lus tsis muaj nuj nqis yog qhov kev pom zoo uas tsis muaj kev cai lij choj txhua yam vim muaj qee yam tsis xws luag. Nws suav tias tsis muaj thiab tsis muaj nyob txij thaum pib thiab tsis tuaj yeem pom zoo los ntawm txoj cai. Daim ntawv cog lus tsis zoo no yog qhov 'kev cog lus tsis muaj tseeb' vim tias 'kev cog lus' yuav tsum muaj txoj cai lij choj.
Puas yog ib qho lus ceeb toom lossis cov lus qhia?
suspiciously adverb (DOUBT) nyob rau hauv ib txoj kev uas ua rau koj xav tias ib yam dab tsi tsis ncaj ncees lawm: Nws ntsia nws suspiciously. Cov menyuam yaus nyob ntsiag to (=nyob ntsiag to tias tej zaum lawv yuav ua yam tsis raug cai). Is supiciously adjective?
Puas yog cov roj chlorine yog cov khoom lossis cov khoom sib xyaw?
Chlorine yog nyob rau hauv pawg 17 ntawm lub sij hawm lub sij hawm, tseem hu ua lub halogens, thiab tsis pom raws li lub caij nyob rau hauv cov xwm - tsuas yog ib tug compound. Feem ntau ntawm cov no yog ntsev, los yog sodium chloride, thiab cov poov tshuaj compounds sylvite (los yog potassium chloride) thiab carnallite (potassium magnesium chloride hexahydrate).
Koj puas paub cov lus tseeb txog cov txiv ntoo?
Zoo Qhov Tseeb. Shrews yog suav tias yog 4 tus neeg vam meej tshaj plaws tsiaj hauv ntiaj teb. Nyob rau lub caij ntuj no, shrews yuav poob mus txog 40% ntawm lawv lub cev hnyav, txo qis mus rau qhov loj ntawm lawv cov pob txha thiab cov kabmob.
Puas yog cov nroj tsuag carnivorous yog cov tsim khoom lossis cov neeg siv khoom?
As producers, cov nroj tsuag tsim lub hauv paus ntawm yuav luag txhua cov khoom noj hauv ntiaj teb. Carnivorous nroj tsuag zoo li "tig rooj" thaum lawv ua raws li cov neeg siv khoom, gobbling kab, qav, thiab cov tsiaj me me. Puas yog Venus flytrap yog tus neeg siv khoom thiab tsim khoom?
