Puas yog lub koom haum yog lub rooj?
Puas yog lub koom haum yog lub rooj?

Video: Puas yog lub koom haum yog lub rooj?

Video: Puas yog lub koom haum yog lub rooj?
Video: Lis Yaj Pov : Lub Hom Phiaj 2024, Kaum ib hlis
Anonim

Cov ntaub ntawv khaws cia hauv koj li rooj , thaum retrieved thiab hloov dua siab tshiab rau hauv ib yam khoom, ces yog ib lub koom haum . Nyob rau hauv ib tug database qhov chaw yog a rooj . Cov rooj sawv cev rau txhua lub tswv yim hauv ntiaj teb tiag tiag uas koj tab tom sim ua qauv (tus neeg, kev lag luam, kev tshwm sim). Contraints tuaj yeem sawv cev kev sib raug zoo ntawm cov koom haum.

Ua li no, qhov txawv ntawm ib qho chaw thiab lub rooj yog dab tsi?

Thawj qhov sib txawv ntawm qhov chaw thiab table hauv a database, yog qhov ntawd qhov chaw tsis muaj nyob hauv a database los yog hauv SQL. Nws yog conceptual. Yog ib rooj yog lub cev tsim hauv a database thiab SQL. Ib txhia cov koom haum tuaj yeem paub daws teeb meem thiab tsis tau hloov dua siab tshiab rau hauv rooj.

Ib yam li ntawd, qhov piv txwv ntawm ib lub koom haum yog dab tsi? Piv txwv ntawm ib qho chaw yog ib tus neeg, ib yam khoom, lossis ib lub koom haum. Qhov chaw hom. Ib tug neeg, lub koom haum, hom khoom, lossis lub tswv yim txog cov ntaub ntawv twg yog khaws cia.

Cov lus nug tseem yog, qhov chaw yog dab tsi?

Ib qhov chaw yog ib qho lus, txheeb xyuas tau thiab cais cov khoom. Nws hais txog cov tib neeg, cov koom haum, cov kab ke, cov ntaub ntawv me me lossis txawm tias cov kab ke sib txawv uas suav tias yog qhov tseem ceeb hauv thiab ntawm lawv tus kheej.

Dab tsi yog qhov chaw nyob hauv database?

Lesson Summary Ib qhov chaw yog ib yam khoom hais txog cov ntaub ntawv yuav tsum tau ntes. Cov yam ntxwv ntawm ib qhov chaw ntxiv txhais cov ntaub ntawv khaws cia. Rau database kev ua tau zoo, qee tus cwj pwm ua cov koom haum . Cov koom haum kuj tau koom ua ke hauv kev sib raug zoo. Ib hom tseem ceeb yog tus yuam sij.

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