Ubale Wachidindo

Chiyanjano cha chiyanjano ndi msana wa zolemba zonse zogwirizana

Chiyanjano chimakhazikitsidwa pakati pa matebulo awiri a mndandanda pamene tebulo limodzi liri ndi fungulo lachilendo lomwe limatchula chinsinsi chachikulu cha tebulo lina. Ichi ndi mfundo yaikulu pamapeto a term relational database.

Mmene Mgwirizano Wachilendo Ukugwiritsira Ntchito Kukhazikitsa Ubale

Tiyeni tione zofunikira za makiyi apamwamba ndi akunja. Chifungulo chapadera chimadziwika bwino pamtundu uliwonse. Ndi mtundu wa fungulo la ovomerezeka lomwe kaŵirikaŵiri ndilo ndime yoyamba mu tebulo ndipo ikhoza kupangidwa mwachinsinsi ndi deta kuti iwonetsetse kuti ili yapadera.

Chifungulo chachilendo ndifungulo lina (osati chimake chachikulu) chomwe chimagwiritsidwa ntchito kulumikiza mbiri ku deta ina.

Mwachitsanzo, ganizirani matebulo awiri omwe amasonyeza kuti mphunzitsi amaphunzitsa njira iti.

Pano, chinsinsi choyambirira cha tableti ndi Course_ID. Chifungulo chake chachilendo ndi Teacher_ID:

Milandu
Chifukwa_ID Chifukwa cha_Name Mphunzitsi_ID
Chifukwa_001 Biology Mphunzitsi_001
Chifukwa_002 Masamu Mphunzitsi_001
Chifukwa_003 Chingerezi Mphunzitsi_003

Mukhoza kuona kuti fungulo lachilendo ku Maphunziro likugwirizana ndi chinsinsi chachikulu mwa aphunzitsi:

Aphunzitsi
Mphunzitsi_ID Teacher_Name
Mphunzitsi_001 Carmen
Mphunzitsi_002 Veronica
Mphunzitsi_003 Jorge

Tikhoza kunena kuti Mphunzitsi Wachifwamba_ID wamtundu wakunja wathandiza kukhazikitsa mgwirizano pakati pa magulu a maphunziro ndi aphunzitsi.

Mitundu ya Maubwenzi Othandizira

Pogwiritsa ntchito makiyi achilendo, kapena mafungulo ena, mungathe kukhazikitsa mitundu itatu ya ubale pakati pa matebulo:

Mmodzi-ndi-mmodzi : Ubale wamtunduwu umalola mbiri imodzi kumbali zonse za ubale.

Mfungulo wapadera umagwirizana ndi zolembera imodzi - kapena ayi - patebulo lina. Mwachitsanzo, muukwati, mwamuna kapena mkazi ali ndi mwamuna mmodzi yekha. Ubale wamtundu umenewu ukhoza kugwiritsidwa ntchito patebulo limodzi ndipo sagwiritsa ntchito makiyi akunja.

Mmodzi-ndi-ambiri : Ubale umodzi ndi wambiri umalola kuti limodzi lokhala limodzi pa tebulo limodzi likhale logwirizana ndi zolemba zambiri mu tebulo lina.

Ganizirani bizinesi yomwe ili ndi deta yomwe ili ndi Amakhasimende ndi matebulo Olemba.

Wothandizira mmodzi angathe kugula maulamuliro angapo, koma lamulo limodzi silingagwirizane ndi makasitomala ambiri. Kotero, tebulo la Malamulo likhoza kukhala ndi fungulo lachilendo lomwe likufanana ndi chinsinsi choyamba cha Otsatsa, pomwe odyera Amsika sakanakhala ndi chinsinsi chachilendo cholozera pa tebulo la Malamulo.

Ambiri-kwa-ambiri : Umenewu ndi mgwirizano wovuta momwe malemba ambiri omwe ali mu tebulo akhoza kugwirizanitsa ndi zolemba zambiri mu tebulo lina. Mwachitsanzo, bizinesi yathu mwina sichifunikira Osangulutsa ndi Maadiresi a Malamulo, koma mwina amafunanso Zamagetsi.

Apanso, ubale pakati pa Amakhasimende ndi Ma tebulo amodzi ndi ambiri, koma ganizirani mgwirizano pakati pa Malamulo ndi Zamakono. Lamulo likhoza kukhala ndi zinthu zambiri, ndipo mankhwala angagwirizane ndi maulamuliro angapo: makasitomala angapo angapereke lamulo lomwe liri ndi zinthu zomwezo. Ubale wamtundu uwu umafuna pa tebulo zitatu.

Kodi Database Relationships N'chiyani?

Kukhazikitsa mgwirizano wogwirizana pakati pa magome a detauni kumathandizira kuonetsetsa kuti chidziwitso cha deta chilipo, zomwe zimapangitsa kuti chiwerengerochi chikhale chokhazikika. Mwachitsanzo, bwanji ngati sitinagwirizanitse matebulo aliwonse kudzera mu fungulo lachilendo koma mmalo mwake munagwirizanitsa deta m'matauni a Gulu ndi Aphunzitsi, monga momwe:

Aphunzitsi ndi Maphunziro
Mphunzitsi_ID Teacher_Name Inde
Mphunzitsi_001 Carmen Biology, Math
Mphunzitsi_002 Veronica Masamu
Mphunzitsi_003 Jorge Chingerezi

Kukonzekera kumeneku kumakhala kovuta ndipo kumaphwanya lamulo loyamba la kafukufuku wachinsinsi, Fomu Yoyamba Yoyamba (1NF), yomwe imanena kuti selo iliyonse ya tebulo iyenera kukhala ndi deta imodzi, yosadziwika.

Kapena mwinamwake ife tinaganiza zowonjezera kachiwiri kachiwiri kwa Carmen, kuti titsimikizire 1NF:

Aphunzitsi ndi Maphunziro
Mphunzitsi_ID Teacher_Name Inde
Mphunzitsi_001 Carmen Biology
Mphunzitsi_001 Carmen Masamu
Mphunzitsi_002 Veronica Masamu
Mphunzitsi_003 Jorge Chingerezi

Izi ndizopangidwe zofooka, kuyambitsa kuphatikiza kosafunikira ndi zomwe zimatchedwa deta kulembetsa anomalies , zomwe zimangotanthauza kuti zingapangitse deta yosagwirizana.

Mwachitsanzo, ngati mphunzitsi ali ndi zolemba zambiri, nanga bwanji ngati deta inafunika kusinthidwa, koma munthu yemwe akupanga kusintha kwa deta sakudziwa kuti zolemba zambiri zilipo? Tebulo likhoza kukhala ndi deta yosiyana kwa munthu yemweyo, popanda njira yeniyeni yowunikira kapena kupewa.

Kuphwanyiratu tebulo ili m'matawuni awiri, aphunzitsi ndi maphunziro (monga momwe tawonedwera pamwambapa), zimapanga mgwirizano woyenera pakati pa deta ndipo zimathandizira kuti deta ikhale yogwirizana komanso yolondola.