ER Diagram vs Class Diagram
ER (qhov chaw-kev sib raug zoo) daim duab thiab cov duab kos hauv chav kawm yog ob qho ntawm cov qauv tsim uas cov software tsim tawm feem ntau tsim thaum lub sijhawm tsim qauv ntawm software engineering lub neej voj voog. ER daim duab yog ib yam khoom ntawm qhov chaw-kev sib raug zoo qauv qauv (ERM) txheej txheem rau qauv databases. Ib daim duab kos duab, sau hauv Unified Modeling Language, yog ib daim duab uas piav txog cov qauv ntawm cov txheej txheem npaj. Txawm hais tias tsis muaj qhov yuav tsum tau muaj qhov tseeb ib qho rau ib daim ntawv qhia nruab nrab ntawm cov chav kawm hauv cov duab kos duab thiab cov chaw hauv cov duab kos duab, feem ntau muaj qee qhov kev sib raug zoo ntawm lawv. Txawm li cas los xij, muaj ntau lub sijhawm uas ib lub koom haum ntawm ER daim duab qhia chaw rau ntau chav kawm ntawm daim duab qhia hauv chav kawm lossis ib chav kawm ntawm daim duab kos duab rau ntau qhov chaw ntawm ER daim duab sib thooj. Tab sis, qhov no nyob ntawm qhov kev xaiv tsim ntawm software developers.
ER Daim duab yog dab tsi?
ER daim duab yog cov khoom lag luam ntawm kev sib raug zoo qauv. Entity-relationship modeling yog tus txheej txheem los nrog kev paub daws teeb meem thiab kev xav sawv cev ntawm cov ntaub ntawv. ER daim duab thaum kawg qauv cov databases. Tshwj xeeb tshaj yog, nws tsim cov tswv yim schema ntawm cov ntaub ntawv qauv. Lub tsev tseem ceeb ntawm ER daim duab kos yog cov chaw, kev sib raug zoo thiab cov cwj pwm. Ib lub koom haum sawv cev rau ib yam khoom uas tuaj yeem muaj nyob ntawm nws tus kheej thiab tuaj yeem txhais tau tshwj xeeb. Feem ntau, ib lub koom haum sawv cev rau lub ntiaj teb tiag tiag khoom xws li lub tsheb lossis tus neeg ua haujlwm. Cov koom haum tuaj yeem yog cov npe uas tuaj thaum lub sijhawm piav qhia ntawm qhov teeb meem yuav daws tau. Kev sib raug zoo qhia tau hais tias cov koom haum sib txuas li cas. Lawv zoo li cov lus qhia pom hauv cov lus piav qhia ntawm qhov teeb meem yuav daws tau. Cov khoom ntawm ob qhov chaw thiab cov khoom yog hu ua tus cwj pwm.
Dab tsi yog Class Diagram?
Daim duab qhia chav kawm (ntau qhov raug hu ua UML class diagram) yog daim duab tsim uas sawv cev rau cov qauv zoo li qub thiab tus cwj pwm ntawm cov txheej txheem npaj, txhais siv UML (Unified Modeling Language). Ib daim duab kos duab qhia cov kab ke hauv chav kawm, kev sib raug zoo ntawm cov chav kawm, thiab lawv cov cwj pwm. Cov chav kawm piav qhia txog qhov tsis txaus ntseeg ntawm cov khoom hauv ntiaj teb tiag tiag, thaum kev sib raug zoo piav qhia tias txhua chav kawm txuas nrog lwm tus li cas. Ob chav kawm thiab kev sib raug zoo muaj cov khoom hu ua tus cwj pwm. Cov txheej txheem hauv cov chav kawm sawv cev lossis txhais tus cwj pwm ntawm cov chav kawm no. Cov txheej txheem thiab cov cwj pwm ntawm cov chav kawm yog hu ua cov tswv cuab ntawm chav kawm.
Dab tsi yog qhov txawv ntawm ER Diagram thiab Class Diagram?
Txawm hais tias ER daim duab thiab daim duab qhia chav kawm yog ob qho ntawm cov qauv tsim cov duab tsim feem ntau tuaj nyob rau lub sijhawm tsim qauv ntawm software engineering tej yaam num, lawv muaj lawv qhov sib txawv tseem ceeb. ER daim duab sawv cev rau cov duab tsis pom tseeb ntawm cov qauv ntaub ntawv, thaum cov duab kos duab sawv cev rau cov qauv zoo li qub thiab kev coj tus cwj pwm ntawm cov txheej txheem npaj. Lub tsev tseem ceeb ntawm ER daim duab kos yog cov chaw, kev sib raug zoo thiab cov cwj pwm tab sis lub ntsiab lub tsev thaiv ntawm cov duab kos yog cov chav kawm, kev sib raug zoo thiab cov cwj pwm. Daim duab kos duab hauv chav kawm muaj feem ntau yuav ua rau hauv cov khoom siv tiag tiag, thaum ER daim duab qhia feem ntau qhia rau hauv cov ntxhuav hauv cov ntaub ntawv. Feem ntau, kev sib raug zoo nyob hauv ER daim duab yog qhov nyuaj rau kev nkag siab rau tib neeg dua li kev sib raug zoo hauv cov duab kos duab.
