Shandisa zviratidzo zveE ER kuratidzira ukama pakati pezvinyorwa zvemashoko
Chimwe chikwata-hukama hwechimiro chimiro chinonyanya kujekesa chinoratidzira ukama huri pakati pezvinyorwa mu database . Mifananidzo DZ dzinowanzoshandisa zviratidzo kuti dzimirire marudzi matatu emashoko: masangano (kana pfungwa), hukama uye hunhu. Mumakambani emuenzaniso ER ER, mabhokisi anoshandiswa kumirira masangano. Daimondi inoshandiswa kureva ukama, uye mavhiri anoshandiswa kureva maitiro.
Kunyangwe kune ziso risina kudzidziswa, sangano-hukama hwemifananidzo hunogona kutarisa zvisinganzwisisiki zvakaoma, kune vadzidzisi vanoziva, vanobatsira vashandi vebhizimisi kunzwisisa zvivako zvemashoko epamusoro asi vasingafambi nemashoko.
Vashandi vepa database vanoshandisa ER zviratidzo zvekufananidza hukama pakati pezvinyorwa zvepa database zviri pachena. Many software software packed automated methods to generate ER diagrams from existing database.
Chimbofunga muenzaniso wepa database uneruzivo pamusoro pevagari veguta. IEE diagram yakaratidzwa mumufananidzo unoenderana nechikamu chino ine zvinhu zviviri: Munhu uye Guta. Imwechete "Upenyu Huri" hukama huri pamwe chete. Munhu mumwe nomumwe anogara muguta rimwechete, asi guta rimwe nerimwe rinogona kuwanisa vanhu vakawanda. Mumufananidzo, mifananidzo ndeye zita romunhu uye yeguta revanhu. Muchidimbu, mazita anoshandiswa kurondedzera masangano nemafungiro, asi mazwi anoshandiswa kurondedzera ukama.
Masangano
Chinhu chimwe nechimwe chaunotarisa mune imwe database ndechechibatanidzwa, uye chimwe nechimwe chine tafura mudhesi rekudanana. Kazhinji, chimwe nechimwe chiri mu database chinowanikwa nemutsara. Kana iwe une dheta rine mazita evanhu, sangano racho rinogona kunzi "Munhu." Tafura ine zita rimwe chete yaizovapo mune dhesi, uye munhu wose aizotarirwa mumutsara muMunhu wefurafura.
Unhu
Databases rine ruzivo pamusoro peimwe sangano. Aya mashoko anonzi "unhu." uye inoumbwa neruzivo rwakasiyana kune rimwe nerimwe rakarongwa. MuMuenzaniso weMunhu, zviito zvinogona kusanganisira zita rokutanga, zita rekupedzisira, kuberekwa uye nhamba inozivikanwa. Unhu hunopa ruzivo rwakakwana pamusoro pechinhu. Mune nheyo yezvekodzero, maitiro anowanikwa muminda umo ruzivo mukati mechirangaridzo rwunoitwa. Iwe hausi uwandu kune imwe nhamba yemafungiro.
Ukama
Kukosha kwechikwata-hukama hwechikwata huri mune kukwanisa kwayo kuratidza ruzivo pamusoro pehukama pakati pezvikamu. Mumuenzaniso wedu, unokwanisa kutarisa ruzivo pamusoro peguta iro munhu umwe neumwe anorarama. Iwe unogonawo kutarisa ruzivo pamusoro peguta pacharo mune Guta rakashamwaridzana neukama hunosungirirana pamwe nevanhu uye Guta ruzivo.
Nzira Yokugadzira sei ER Diagram
- Gadzira bhokisi rimwe nerimwe sangano kana pfungwa inoenderana nemuenzaniso wako.
- Dhirosa mitsetse kuti ubatanidze zvikwata zvakabatana kuti uenzanise hukama. Nyora uhu hukama huchishandisa mashoko mukati me diamond maumbirwo.
- Tsvaga hunoenderana nemafungiro ehurumende yega yega, kutanga nemafungiro anokosha, uye uvaise mumashizha mumufananidzo. Gare gare, unogona kuita chirevo chako chinonyatsotsanangura.
Kana wapedza, iwe uchave wakanyatsoratidzira kuti maitiro emabhizimusi akasiyana akasiyana sei, uye iwe uchava nechinangwa chekugadzirisa dhesi rekodzero yekutsigira bhizinesi rako.