Dab tsi yog tus cwj pwm hauv kev sib raug zoo ntawm daim duab?
Dab tsi yog tus cwj pwm hauv kev sib raug zoo ntawm daim duab?

Video: Dab tsi yog tus cwj pwm hauv kev sib raug zoo ntawm daim duab?

Video: Dab tsi yog tus cwj pwm hauv kev sib raug zoo ntawm daim duab?
Video: Saib Mis paub Poj niam (hluas nkauj) tus yam ntxwv lub siab 2024, Lub peb hlis ntuj
Anonim

Ib daim duab qhia kev sib raug zoo (ERD) qhia cov kev sib raug zoo ntawm qhov chaw teev cia nyob rau hauv ib tug database. Cov cov koom haum tuaj yeem muaj yam ntxwv uas txhais nws cov khoom. Los ntawm kev txhais cov cov koom haum , lawv yam ntxwv , thiab qhia cov kev sib raug zoo nruab nrab ntawm lawv, ib ER daim duab illustrates lub logical qauv ntawmdatabases.

Piv txwv li, dab tsi yog qhov chaw thiab kev sib raug zoo?

Cov koom haum , Kev sib raug zoo , thiab Yam ntxwv . Piv txwv li, PERSON denotes the cov koom haum ntawm ib qhov chaw -set nrog yam ntxwv NPE thiab AGE, thaum ASSIGNED qhia txog qhov kev sib raug zoo nruab nrab ntawm cov koom haum ntawm qhov chaw - teev PERSON thiab PROJECT. Yam ntxwv coj lawv cov txiaj ntsig los ntawm cov hauv paus primitivedomains hu ua value-sets.

Ib sab saum toj no, Dab tsi yog Entity Relationship Diagram nrog piv txwv? Ib qhov chaw yog ib yam khoom lossis cov ntaub ntawv. Ib qhov chaw yog sawv cev ua duab plaub hauv ib ER daim duab . Rau piv txwv : Hauv qab no ER daim duab peb muaj ob cov koom haum Tub ntxhais kawm thiab College thiab ob qho no cov koom haum muaj ntau rau ib kev sib raug zoo raws li ntau tus tub ntxhais kawm kawm hauv asingle college.

Tsis tas li ntawd, Entity Relationship Diagram yog dab tsi?

Ib kev sib raug zoo qauv, kuj hu ua ib qhov chaw - kev sib raug zoo ( ER ) daim duab , yog agraphical sawv cev ntawm cov koom haum thiab lawv kev sib raug zoo rau ib leeg, feem ntau yog siv hauv kev suav nrog rau lub koom haum ntawm cov ntaub ntawv hauv databases lossis cov ntaub ntawv xov xwm.

Vim li cas peb thiaj siv ER daim duab?

Database troubleshooting: ER daim duab yog siv txhawm rau txheeb xyuas cov ntaub ntawv uas twb muaj lawm los nrhiav thiab daws cov teeb meem hauv logic lossis kev xa tawm. Kev kos duab daim duab yuav tsum qhia qhov twg nws mus tsis ncaj ncees lawm. Business Information Systems: Cov daim duab yog siv tsim lossis txheeb xyuas cov ntaub ntawv sib raug zoo siv hauv kev ua lag luam.

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