I-superkey ingummiselo ongasetyenziselwa ukuchonga irekodi yedatha
I-superkey ingaba enye okanye udibaniso lweempawu ezingasetyenziselwa ukuchonga ngokukodwa irekhodi yeenkcukacha. Itheyibhile inokuba nenhlanganisela emininzi eyenza ama-superkeys.
Umzekelo ophezulu
Itheyibhile eneenkalo , , kunye , umzekelo, uninzi lwee-superkeys ezinokwenzeka. I-superkeys ezintathu zingu , kunye ne-SSN, Igama>.
| Igama | Ubudala | SSN | Ifowuni Ext. |
|---|
| URobert Jones | 43 | 123-45-6789 | 123 |
| EBeth Smith | 43 | 234-56-7890 | 456 |
| URobert Jones | 18 | 345-67-8901 | 789 |
Njengoko ubona, iikholam ze kunye zinamaxwebhu amaninzi anolwazi olufanayo. Ngelixa ikholomu ye- ingasetyenziselwa ukufumana umntu, isandiso sefowuni sinokutshintshwa.
Iintlobo ze-Superkeys
Kulabo abalwe kwitheyibhile elingentla, kuphela yikhibhodi yomviwa , okuyi-subset ekhethekileyo yama-superkeys ezisebenzisa inani elincinci leempawu zokuzikhethela ngokukodwa irekhodi. Ezinye iikholomu ziqulethe ulwazi olungabalulekanga ukuchonga iirekhodi.
I ingathunyelwa kwakhona njengekhiyi encinci okanye i-superkey encinci kuba iqulethe inani elincinane leenkcukacha ezifunekayo ukuchonga irekhodi ngalinye. Ngaphandle kwemigca efanayo, inqakrazo eyona nto ingaba yinto ephezulu kunye nencoko encinci ngenxa yokuba kufuneka ilandele irekhodi kuphela, kwaye kufuneka ukuba yinto encinci ukuba iguqule.
Ukuba itheyibhile yayingenayo ikholomu ke umqeshi angakha amanani omsebenzi ukuze akwazi ukubona abantu.
Amanani omsebenzi omtsha aya kuthiwa yinto ephambili yokuphambili. Olu khetho oluphambili luya kusebenza njenge-superkey.