Video: Dab tsi yog lub rooj sib tham hauv kev sib raug zoo?
2024 Tus sau: Lynn Donovan | [email protected]. Kawg hloov kho: 2023-12-15 23:47
Ib associative rooj yog qhov tsis tseem ceeb rooj uas nws lub ntsiab tseem ceeb yog txhua tus yuam sij txawv teb chaws. Vim cov rooj sib tham qauv ntshiab kev sib raug zoo es tsis yog cov koom haum, cov kab ntawm ib qho associative rooj tsis sawv cev rau cov koom haum. Xwb, lawv piav txog tus kev sib raug zoo ntawm cov koom haum rooj sawv cev.
Tsis tas li ntawd, dab tsi yog qhov piv txwv ntawm kev sib koom ua ke?
Ib koom haum koom haum yog lub rooj uas koom nrog ob lub rooj sib tham hauv ntau qhov kev sib raug zoo. Ib koom nrog kev sib raug zoo attribute yog tus cwj pwm ntawm tus koom haum koom haum uas tshwm sim vim muaj ntau rau ntau txoj kev sib raug zoo. Ntawm no yog ib qho piv txwv . Nws yog tus cwj pwm ntawm lub koom haum.
Tsis tas li ntawd, thaum twg kev sib raug zoo yuav tsum tau hloov mus rau ib qho chaw koom nrog? 1 Teb. Associative cov koom haum yog siv thaum koj xav tau a kev sib raug zoo los koom nrog a kev sib raug zoo . Rau ib txwm ntau-rau-ntau kev sib raug zoo nruab nrab ntawm Tub Ntxhais Kawm thiab Chav Kawm, peb tsuas yog siv pob zeb diamond xwb. Txawm li cas los xij, yog tias peb xav koom nrog Kev Sau Npe nrog Xib Fwb, peb ua tau tig Enrollment rau hauv ib qho koom haum koom haum.
Ib yam li ntawd, koj tuaj yeem nug, dab tsi yog hom koom haum koom nrog?
Ib koom haum koom haum yog ib lo lus siv nyob rau hauv relational thiab qhov chaw - kev sib raug zoo txoj kev xav. Cov ntaub ntawv kev sib raug zoo yuav tsum tau ua raws li kev sib raug zoo ntawm lub hauv paus (los yog lub hauv paus rooj) los daws ntau qhov kev sib raug zoo. Ib qho kev sib raug zoo sawv cev rau qhov no zoo ntawm qhov chaw hu ua, tsis raws cai, ib koom nrog rooj.
Kev sib raug zoo 1 N yog dab tsi?
1 -rau-ntau, los yog 1 : N kev sib raug zoo , yog siv thaum koj tsim ib kev sib raug zoo nruab nrab ntawm ob qhov chaw uas muaj ntau cov ntaub ntawv los ntawm ib qhov chaw cuam tshuam nrog ib qho ntaub ntawv los ntawm lwm qhov chaw. Hauv layman cov ntsiab lus, qhov no txhais tau hais tias thaum koj muaj niam txiv (los yog thawj) qhov chaw thiab ntau yam (los yog menyuam) cov koom haum.
Pom zoo:
Vim li cas kev sib raug zoo algebra siv nyob rau hauv kev sib raug zoo database tswj?
RELATIONAL ALGEBRA yog ib hom lus nug uas siv dav heev. Nws sau cov xwm txheej ntawm kev sib raug zoo raws li kev tawm tswv yim thiab muab qhov tshwm sim ntawm kev sib raug zoo raws li cov zis. Nws siv ntau yam haujlwm los ua qhov haujlwm no. Relational algebra operations yog ua recursively ntawm kev sib raug zoo
Dab tsi yog kev sib tshuam hauv kev sib raug zoo algebra?
INTERSECTION kev khiav hauj lwm nyob rau hauv RELATIONAL ALGEBRA. Kev sib tshuam ntawm teeb A thiab B = A ∩ B = {1, 6} Cov ntsiab lus uas muaj nyob rau hauv ob qho tib si A thiab B yuav tsuas muaj nyob rau hauv lub teeb tau los ntawm kev sib tshuam ntawm A thiab B
Dab tsi yog qhov txawv ntawm kev sib raug zoo unary kev sib raug zoo binary thiab kev sib raug zoo ternary?
Kev sib raug zoo tsis sib xws yog thaum ob tus neeg koom hauv kev sib raug zoo yog tib lub koom haum. Piv txwv li: Cov ncauj lus yuav yog qhov yuav tsum tau ua ua ntej rau lwm yam kev kawm. Kev sib raug zoo ternary yog thaum peb lub koom haum koom nrog kev sib raug zoo
Dab tsi yog qhov txawv ntawm kev sib raug zoo thiab tsis muaj kev sib raug zoo databases?
Qhov sib txawv loj ntawm lawv yog li cas lawv tuav cov ntaub ntawv. Relational databases are structured.Non-relational databases are document-oriented. Qhov no hu ua cov ntaub ntawv hom cia tso cai ntau 'qeb' ntawm cov ntaub ntawv khaws cia hauv ib qho kev tsim lossis Cov Ntaub Ntawv
Dab tsi yog qee qhov tsis zoo ntawm lub sijhawm stamping txoj hauv kev rau kev tswj hwm kev sib raug zoo?
Qhov tsis zoo ntawm lub sij hawm stamping mus kom ze yog tias txhua tus nqi khaws cia hauv cov ntaub ntawv yuav tsum muaj ob lub sij hawm thwj ntxiv: ib qho rau lub sijhawm kawg ntawm daim teb tau nyeem thiab ib qho rau qhov hloov tshiab kawg. Lub sij hawm stamping yog li ua rau kom nco xav tau thiab cov ntaub ntawv ua haujlwm nyiaj siv ua haujlwm