Video: Vim li cas kev sib raug zoo algebra siv nyob rau hauv kev sib raug zoo database tswj?
2024 Tus sau: Lynn Donovan | [email protected]. Kawg hloov kho: 2023-12-15 23:47
RELATIONAL ALGEBRA yog dav siv txheej txheem lus nug. 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 kev khiav hauj lwm yog ua recursively ntawm a kev sib raug zoo.
Ntxiv mus, vim li cas kev sib raug zoo algebra tseem ceeb?
Cov kev sib raug zoo algebra yog heev tseem ceeb rau ob peb lub laj thawj: 1. nws muab lub hauv paus tsim nyog rau kev sib raug zoo qauv kev ua haujlwm. Raws li qhov algebra txhais cov txheej txheem kev ua haujlwm rau cov kev sib raug zoo model, ua kev sib raug zoo calculus muab cov lus tshaj tawm qib siab dua rau kev qhia meej kev sib raug zoo lus nug.
Qhov thib ob, 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.
Ib yam li ntawd, nws tau nug, qhov twg yog kev sib raug zoo algebra siv?
Relational Algebra yog cov lus nug txheej txheem, uas yuav siv Kev Sib Raug Zoo li kev tawm tswv yim thiab tsim kom muaj kev sib raug zoo raws li cov zis. Relational algebra mas muab theoretical foundation rau kev sib raug zoo databases thiab SQL. Projection yog siv rau qhov project xav tau kab ntawv los ntawm kev sib raug zoo.
Relational algebra piav nrog piv txwv yog dab tsi?
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. |
Pom 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?
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Dab tsi yog qee qhov tsis zoo ntawm lub sijhawm stamping txoj hauv kev rau kev tswj hwm kev sib raug zoo?
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Dab tsi yog qhov kev siv ntawm kev sib raug zoo algebra hauv DBMS?
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
Yuav ua li cas koj tsim ib tug rau ntau txoj kev sib raug zoo nyob rau hauv ib tug database system?
Txhawm rau tsim kom muaj kev sib raug zoo ib leeg rau ob qho tib si ntawm thaj chaw (feem ntau yog thawj qhov tseem ceeb thiab txawv teb chaws qhov tseem ceeb) yuav tsum muaj qhov ntsuas tshwj xeeb. Txhawm rau tsim kom muaj kev sib raug zoo ib-rau-ntau Lub teb ntawm ib sab (feem ntau yog qhov tseem ceeb) ntawm kev sib raug zoo yuav tsum muaj qhov ntsuas tshwj xeeb