Video: Cov kab ntawv database hu ua dab tsi?
2024 Tus sau: Lynn Donovan | [email protected]. Kawg hloov kho: 2023-12-15 23:47
Hauv kev sib raug zoo database , a kem yog ib txheej ntawm cov ntaub ntawv muaj nuj nqis ntawm ib yam yooj yim, ib tug nqi rau txhua kab ntawm cov database . A kem tuaj yeem yog hu ua ib attribute. Txhua kab yuav muab cov ntaub ntawv tus nqi rau txhua tus kem thiab ces yuav to taub raws li ib tug qauv ntaub ntawv tus nqi.
Ib yam li ntawd, nws raug nug, kab ntawv hu ua dab tsi?
Lub Sijhawm Teev Taw: Tsev Neeg thiab Lub Sijhawm. Nyob rau hauv lub sij hawm ntawm lub ntsiab lus, muaj xya kab rov tav kab ntawm lub ntsiab hu ua lub sij hawm. Qhov ntsug kab ntawm cov ntsiab lus yog hu ua pab pawg, lossis tsev neeg. Feem ntau txoj kev uas lub sij hawm teem sij hawm yog cais los ntawm hlau, nonmetals, thiab metalloids.
Tsis tas li ntawd, kab thiab kab hauv database yog dab tsi? Hauv cov ntsiab lus yooj yim, a database rooj tuaj yeem xav tias muaj kab thiab kab . Txhua kab nyob rau hauv ib lub rooj sawv cev ib pawg ntawm cov ntaub ntawv ntsig txog, thiab txhua kab nyob rau hauv lub rooj muaj tib lub qauv. Piv txwv li, hauv ib lub rooj uas sawv cev rau cov tuam txhab, txhua tus kab yuav sawv cev ib lub tuam txhab.
Ib yam li ntawd, nws yog nug, dab tsi yog ib kem hauv Table?
Nyob rau hauv kev sib raug zoo database, a kem yog ib pawg ntsug ntawm cov hlwb hauv ib rooj . Nws kuj tseem siv los piav qhia txog pawg ntsug ntawm cov hlwb hauv cov txiaj ntsig ntawm cov lus nug, lossis lwm yam khoom siv database, xws li kev pom, cov txheej txheem khaws cia, rooj - Muaj nuj nqis ua haujlwm, thiab lwm yam.
3 hom kab yog dab tsi?
Muaj peb Cov kev txiav txim sib txawv hauv Ancient Greek architecture: Doric, Ionic, thiab Corinthian. Cov no peb tau txais los ntawm cov neeg Loos, uas hloov lawv lub peev. Cov Roman saws los ntawm Greek cov lus txib tau tshwm sim nyob rau xyoo pua 1 BC.
Pom zoo:
Dab tsi yog lub hom phiaj ntawm delimiters nyob rau hauv cov ntawv sau npe ob hom ntawv cov ntaub ntawv delimiters?
Cov ntaub ntawv delimited yog cov ntawv nyeem siv los khaws cov ntaub ntawv, uas txhua kab sawv cev rau ib phau ntawv, tuam txhab, lossis lwm yam, thiab txhua kab muaj cov teb sib cais los ntawm tus lej
Cov ntawv cim dab tsi pom nyob rau ntawm kab thib peb ntawm cov keyboard?
Pib los ntawm sab laug thiab txuas mus rau sab xis, kab thib peb suav nrog cov ntawv sib law liag H, I, J, K, E, F, thiab G. Thawj kab ntawm cov keyboard muaj 10 tus tsiaj ntawv yuam sij pib ntawm sab laug ntawm kab thaum saib cov keyboard
Thaum cov lus tau hla tawm cov ntaub ntawv kuaj xyuas feem ntau nthuav tawm cov ntawv sau thawj nrog kev pab ntawm dab tsi?
Infrared luminescence yog siv rau: Qhia tawm cov ntawv sau uas tau muab tshem tawm THIAB kuaj pom yog tias ob tus lej sib txawv tau siv rau hauv kev sau ntawv. Cov kws tshuaj xyuas cov ntaub ntawv feem ntau nthuav tawm cov ntawv sau thawj ntawm cov lus uas tau hla nrog kev pab ntawm: Infrared tawg
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