Video: Cov ntaub ntawv qeb hu ua dab tsi?
2024 Tus sau: Lynn Donovan | [email protected]. Kawg hloov kho: 2023-12-15 23:47
Hauv databases, a cov ntaub ntawv qeb yog hu ua ib BLANK. Teb.
Cov lus nug tseem yog, dab tsi yog cov ntaub ntawv qeb hu ua hauv databases?
Tag nrho cov ntaub ntawv hais txog ib qho feature hauv lub rooj yog hu ua ib cov ntaub ntawv - cov ntaub ntawv tshwm sim tau teem rau hauv kab. Pawg ntawm cov ntaub ntawv yog teem rau hauv kab. Ib columnheading ( Lub npe ) yog hu ua ib teb npe indatabase lus. Tus yuam sij txawv teb chaws yog qhov sib thooj hauv asecond cov ntaub ntawv rooj - tham tom qab.
Qhov thib ob, dab tsi yog qhov sib txawv ntawm cov teb hauv ib lub database? Qee qhov kev sib txawv hom teb yog: Cim, Boolean, Integer, Decimal, Date, thiab Timestamp. Txawv databases qee lub npe hom teb txawv; piv txwv li, cov ntaub ntawv cim hom hauv Excel yog tib yam li cov ntaub ntawv Text hom hauv Access.
Hais txog qhov no, dab tsi yog lub npe teb hauv lub database?
Lub npe teb tej zaum yuav xa mus rau: Hauv computer science, a npe kev txheeb xyuas a teb hauv a database record. In the United Kingdom, the npe ntawm a teb ; lawv txhua tus muaj npe, raws li feem ntau pom nyob rau hauv cov qub pawg ntseeg maps, title maps thiab ntxov thiab pre-Ordnance Survey maps. Geographic designation rau apiece of land (toponymy)
Koj txhais li cas los ntawm hom teb?
Cov hom teb txiav txim qhov hom ntawm cov ntaub ntawv uas tus neeg siv ua tau nkag rau hauv teb (alphanumeric, numeric, hnub tim, thiab lwm yam) los yog txiav txim siab li cas tus teb functions nyob rau hauv lub database, piv txwv li, yog ib tug duab tso tawm nyob rau hauv lub teb thaum tus neeg siv xaiv cov duab cov ntaub ntawv ntawm ib qho kev tso cai hom , ua tus teb txuas mus rau lwm tus teb hauv a
Pom zoo:
Cov ntaub ntawv hom thiab cov qauv ntaub ntawv yog dab tsi?
Cov qauv ntaub ntawv yog ib txoj hauv kev piav qhia txog ib txoj hauv kev los npaj cov ntaub ntawv kom ua haujlwm andalogrithms tuaj yeem siv tau yooj yim dua. Ib hom ntaub ntawv piav qhia txog cov ntaub ntawv uas txhua tus sib koom ua ke. Piv txwv li tus lej cov ntaub ntawv hom piav qhia txhua tus lej uas lub khoos phis tawj tuaj yeem ua tau
Dab tsi yog qhov txawv ntawm XML cov ntaub ntawv thiab cov ntaub ntawv sib txheeb?
Qhov sib txawv loj ntawm XML cov ntaub ntawv thiab cov ntaub ntawv sib txheeb Ib daim ntawv XML muaj cov ntaub ntawv hais txog kev sib raug zoo ntawm cov ntaub ntawv rau ib leeg nyob rau hauv daim ntawv ntawm hierarchy. Nrog rau tus qauv kev sib raug zoo, tib hom kev sib raug zoo uas tuaj yeem txhais tau yog cov lus niam txiv thiab cov rooj sib raug zoo
Dab tsi yog qhov sib txawv ntawm pab pawg cov ntaub ntawv thiab cov ntaub ntawv tsis yog pawg?
Ob leeg yog cov ntaub ntawv muaj txiaj ntsig ntawm cov ntaub ntawv tab sis qhov sib txawv ntawm lawv yog cov ntaub ntawv tsis muaj ntaub ntawv yog rawdata. Qhov no txhais tau hais tias nws nyuam qhuav tau sau tab sis tsis txheeb rau hauv ib pawg lossis cov chav kawm. Ntawm qhov tod tes, groupeddata yog cov ntaub ntawv uas tau teeb tsa ua pawg los ntawm cov ntaub ntawv nyoos
Vim li cas kem taw qhia cov ntaub ntawv khaws cia ua cov ntaub ntawv nkag ntawm disks sai dua li kab qhia cov ntaub ntawv khaws cia?
Kem oriented databases (aka columnar databases) yog qhov tsim nyog rau kev ntsuas kev ua haujlwm ntau dua vim tias cov ntaub ntawv hom ntawv (kem hom) qiv nws tus kheej kom nrawm dua cov lus nug ua - scans, aggregation thiab lwm yam. Ntawm qhov tod tes, kab oriented databases khaws ib kab (thiab tag nrho nws. kab) contiguously
Dab tsi yog cov teeb meem ntawm kev tswj cov ntaub ntawv hauv cov ntaub ntawv ib txwm muaj?
Nyob rau tib lub sijhawm, qhov kev tswj hwm cov ntaub ntawv ib puag ncig tsim teeb meem xws li cov ntaub ntawv rov ua dua thiab tsis sib xws, cov kev pab cuam-cov ntaub ntawv dependence, inflexibility, tsis muaj kev ruaj ntseg, thiab tsis muaj cov ntaub ntawv sib qhia thiab muaj