Video: Koj nkag siab dab tsi los ntawm kev sib raug zoo algebra piav qhia nrog cov qauv tsim nyog?
2024 Tus sau: Lynn Donovan | [email protected]. Kawg hloov kho: 2023-12-15 23:47
Relational Algebra yog cov lus nug txheej txheem siv los nug cov lus database kom nkag mus rau cov ntaub ntawv sib txawv. Hauv kev sib raug zoo algebra , cov tswv yim yog kev sib raug zoo (cov lus los ntawm cov ntaub ntawv yuav tsum tau nkag mus) thiab cov zis kuj yog kev sib raug zoo (ib ntus lub rooj tuav cov ntaub ntawv thov los ntawm tus neeg siv).
Ntawm no, dab tsi yog kev sib raug zoo algebra piav nrog piv txwv?
Cov ntsiab lus
| Kev ua haujlwm | Lub hom phiaj |
|---|---|
| Kev sib tshuam (∩) | Kev sib tshuam txhais ib qho kev sib raug zoo uas muaj cov txheej txheem ntawm tag nrho cov tuple uas nyob hauv ob qho tib si A thiab B. |
| Cartesian khoom (X) | Cartesian kev ua haujlwm yog pab tau rau kev sib koom ua ke ntawm ob qho kev sib raug zoo. |
| Sab hauv koom | Kev koom nrog sab hauv, suav nrog cov tuples uas ua tau raws li cov qauv sib xws. |
Tom qab ntawd, lo lus nug yog, dab tsi yog qhov kev ua haujlwm ntawm kev sib raug zoo algebra? Tsib txoj haujlwm yooj yim hauv kev sib raug zoo algebra: Kev Xaiv, Kev Tshaj Tawm, Cartesian khoom , Union , thiab Teeb qhov txawv.
Cov lus nug tseem yog, koj nkag siab dab tsi los ntawm kev sib raug zoo algebra?
Relational Algebra . Relational algebra yog ib tug txheej txheem query lus, uas yuav siv sij hawm ntawm kev sib raug zoo raws li cov tswv yim thiab yields piv txwv ntawm kev sib raug zoo raws li tso zis. Nws siv cov neeg ua haujlwm los ua cov lus nug. Relational algebra yog ua recursively ntawm kev sib raug zoo thiab cov txiaj ntsig nruab nrab kuj suav tias yog kev sib raug zoo.
Qhov twg hauv qab no yog kev sib raug zoo algebra ua haujlwm?
Qhov twg hauv qab no yog ib qho tseem ceeb kev ua haujlwm hauv kev sib raug zoo algebra ? Piav: Qhov tseem ceeb kev ua haujlwm yog xaiv, project, union, teeb txawv, Cartesian khoom, thiab rename. Piav: Qhov xaiv kev ua haujlwm xaiv tuples uas txaus siab rau ib tug muab predicate.
Pom zoo:
Dab tsi yog qhov txawv ntawm cov khoom taw qhia cov qauv database thiab cov qauv kev sib raug zoo?
Qhov sib txawv ntawm kev sib raug zoo database thiab cov khoom taw qhia cov ntaub ntawv yog tias cov ntaub ntawv sib txheeb cov ntaub ntawv khaws cov ntaub ntawv nyob rau hauv daim ntawv ntawm cov ntxhuav uas muaj kab thiab kab. Hauv cov khoom taw qhia cov ntaub ntawv cov ntaub ntawv khaws cia nrog rau nws cov haujlwm uas ua los yog nyeem cov ntaub ntawv uas twb muaj lawm. Cov no yog qhov sib txawv hauv paus
Puas txhais tau tias yog kev sib raug zoo ntawm cov khoom ntawm ib yam khoom thiab lub peev xwm ntawm tus neeg sawv cev uas muab cov lus qhia rau kev siv cov khoom?
Kev them nyiaj yog kev sib raug zoo ntawm cov khoom ntawm ib yam khoom thiab lub peev xwm ntawm tus neeg sawv cev uas txiav txim siab seb qhov khoom siv tau li cas
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 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