Kodi Kutembenuka Kwambiri Kumakhala ndi Database

Pewani Kusintha Kwambiri Kuthandizira Kuonetsetsa Chikhalidwe

Udindo wodalirika mu databata ndi ubale wosagwirizana pakati pa magulu omwe ali ndi tebulo lomwe limayambitsa kugwiritsidwa ntchito . Kuti mukwaniritse ndondomeko yoyenera ya Fomu Yachiwiri (3NF), muyenera kuchotsa kudalira kulikonse.

Mwa chikhalidwe chake, kudalira kusinthika kumafuna zizindikiro zitatu kapena zingapo (kapena zigawo zachinsinsi) zomwe zimagwira ntchito pakati pawo, kutanthauza kuti Phukusi A mu tebulo likudalira pazomwe B kupyolera mu Pakati C.

Tiyeni tiwone momwe izi zingagwire ntchito.

Chitsanzo Chotsimikizika Chosintha

AUTHORS

Mu AUTHORS chitsanzo pamwambapa:

• Bukhu → Wolemba : Pano, chikhumbo cha Bukhu chimapanga chikhumbo cha Mwini . Ngati mumadziwa dzina la bukhuli, mukhoza kuphunzira dzina la wolemba. Komabe, Wolemba salemba Buku , chifukwa wolemba akhoza kulemba mabuku ambiri. Mwachitsanzo, chifukwa timadziwa dzina la wolemba Orson Scott Card, sitidziwa dzina la bukuli.
• Wolemba → Wolemba_Mulungu : Momwemonso, chikhumbo cha Mlembi chimakhazikitsa Wolemba_Mulungu , koma osati njira yina; Chifukwa chakuti tikudziwa kuti dziko silikutanthauza kuti tikhoza kudziwa wolemba.

Koma tebulo ili limayambira kudalira kotembenuka:

• Bukhu → Author_Nationality: Ngati tidziwa dzina la bukhuli, tingathe kudziwa mtunduwu kudzera mwalemba Walemba .

Pewani Kusintha Kwambiri

Kuti tiwonetseke Fomu Yachiwiri Yachikhalidwe, tiyeni tichotse chidaliro chokhazikika.

Tikhoza kuyamba pochotsa ndondomeko ya Buku kuchokera pa tebulo la Olemba ndikupanga tebulo lapadera la Mabuku:

MABUKU

AUTHORS

Kodi izi zinakonza? Tiyeni tione zokhumba zathu tsopano:

MABUKU :

• Book_ID → Bukhu: Bukhu limadalira pa Bukhu_ID .
• Palibe zodalira zina zomwe zili mu tebulo ili, kotero ndife oyenera. Onani kuti fungulo lachilendo Author_ID limagwirizanitsa tebulo ili ku AUTHORS tebulo kupyolera muchinsinsi chake choyamba Author_ID . Tapanga ubale kuti tipewe kudalira kwachithunzithunzi, kapangidwe kofunikira kazomwe timagwirizana.

Tebulo la AUTHORS :

• Author_ID → Wolemba: Wolemba amadalira Mlembi_ID .
• Wolemba → Wolemba_Mthandizi Wadziko: Mtundu ukhoza kutsimikiziridwa ndi wolemba.
• Author_ID → Wolemba_Mtundu Wathu: Mtundu umatha kudziwika kuchokera kwa Author_ID kupyolera mwazolemba . Timakhalabe ndi chidaliro chosinthika.

Tiyenera kuwonjezera tebulo lachitatu kuti tiwonetsetse deta iyi:

DZIKO

AUTHORS

Tsopano tili ndi matebulo atatu, tikugwiritsa ntchito makiyi akunja oyanjanitsa pakati pa matebulo:

• Gulu lachikhomo la bukhu la OLEMBEDWA Author_ID likugwirizanitsa buku kwa wolemba mu tebulo la AUTHORS.
• Gulu lachilendo la AUTHORS phokoso lachilendo Country_ID likugwirizana ndi wolemba ku dziko ku gombe la COUNTRIES.

• Gome la COUNTRIES liribe fungulo lachilendo chifukwa silikusowa kulumikizana ndi tebulo lina mumapangidwe awa.

Chifukwa Chakudalira Kwambiri Ndi Zoipa Zolemba Zopangidwa

Kodi ubwino wotani kusamalidwa ndikuwathandiza kuti muonetsetse kuti 3NF? Tiyeni tione tebulo lathu loyamba kachiwiri ndikuwona zomwe zimapanga:

AUTHORS

Kukonzekera kotereku kungapangitse kuti deta zolakwika ndi zosagwirizana, mwachitsanzo:

• Ngati mwachotsa mabuku awiriwa "Ana a Maganizo" ndi "Ender's Game," mungachotse mlembiyo "Orson Scott Card" ndi mtundu wake kwathunthu ku database.

• Simungakhoze kuwonjezera wolemba watsopano ku malo osungira pokhapokha ngati muwonjezeranso buku; bwanji ngati mlembiyo sanayambe kusindikizidwa kapena simudziwa dzina la bukhu limene adalemba?
• Ngati "Orson Scott Card" idasintha kukhala nzika yake, muyenera kusintha izo zonse zomwe akuwonekera. Kukhala ndi zolemba zambiri ndi wolemba yemweyo kungapangitse deta yolondola: bwanji ngati munthu wolowa deta sakudziwa kuti pali zolemba zambiri za iye ndikusintha deta mu cholemba chimodzi chokha?
• Simungathe kuchotsa buku ngati "The Tale of Handmaid's Tale" popanda kuchotsa mlembi kwathunthu.

Izi ndi zifukwa zina zomwe zimayendera kuonetsetsa , komanso kupeŵa zodalira, kuteteza deta komanso kuonetsetsa kuti zamasintha.