Gwema Ukuthembela Okuguqukayo Ukusiza Ukuqinisekisa Ukujwayelekile
Ukuthembela okuguquguqukayo ku-database kuyisihlobo esingavamile phakathi kwamagugu etafuleni elifanayo elidala ukuxhomekeka okusebenzayo . Ukuze ufeze izinga elijwayelekile lokuFometha leSithathu Elijwayelekile (3NF), kufanele ususe noma yikuphi ukuthembela okuguquguqukayo.
Ngokwemvelo yayo, ukuthembela okuguquguqukayo kudinga izimfanelo ezintathu noma ngaphezulu (noma amakholomu egciniwe database) anokwethenjelwa kokusebenza phakathi kwabo, okusho ukuthi ikholomu A etafuleni lithembele kukholomu B ngekholomu eliphakathi.
Ake sibone ukuthi lokhu kungase kusebenze kanjani.
Isibonelo sokuthembela okuguquguqukayo
AUTHORS
| Umbhali_ID | Umbhali | Ibhuku | Umbhali_Nationality |
|---|---|---|---|
| Auth_001 | I-Orson Scott Card | I-Ender's Game | I-united states |
| Auth_001 | I-Orson Scott Card | I-Ender's Game | I-united states |
| Auth_002 | UMargaret Atwood | I-Tale's Handmaid's Tale | Canada |
Ku-AUTHORS isibonelo esingenhla:
- Incwadi → Umbhali : Lapha, isici seBhuku sinquma umqondo woMlobi . Uma wazi igama lencwadi, ungafunda igama lomlobi. Noma kunjalo, uMlobi akasinqumi incwadi , ngoba umbhali angabhala izincwadi eziningi. Isibonelo, ngenxa yokuthi siyazi igama lomlobi we-Orson Scott Card, asazi igama lencwadi.
- Umbhali → Umbhali_Nationality : Ngokufanayo, isici seMlothi sinquma u- Author_Nationality , kodwa hhayi enye indlela ezungezile; ngoba nje siyazi ukuthi ubuzwe abusho ukuthi singakwazi ukunquma umbhali.
Kodwa leli tafula lifaka ukuthembela okuguquguqukayo:
- Incwadi → I- Author_Nationality: Uma siyazi igama lencwadi, singakwazi ukunquma ubuzwe ngekholomu yoMlobi.
Ukugwema Ukuthembela Okuguquguqukayo
Ukuze uqinisekise ifomu lesithathu elijwayelekile, ake sisuse ukuthembela okuguquguqukayo.
Singakwazi ukuqala ngokususa ikholomu yencwadi kusuka kuthebula labalobi bese sakha itafula elihlukile lamabhuku:
IZINCWADI
| Book_ID | Ibhuku | Umbhali_ID |
|---|---|---|
| Book_001 | I-Ender's Game | Auth_001 |
| Book_001 | Izingane Zengqondo | Auth_001 |
| Book_002 | I-Tale's Handmaid's Tale | Auth_002 |
AUTHORS
| Umbhali_ID | Umbhali | Umbhali_Nationality |
|---|---|---|
| Auth_001 | I-Orson Scott Card | I-united states |
| Auth_002 | UMargaret Atwood | Canada |
Ingabe lokhu kwalungisa? Ake sihlole izixhasi zethu manje:
IBHAYIBHELI ithebula :
- Book_ID → Incwadi: Incwadi incike kwi- Book_ID .
- Azikho ezinye izixhomeke kuletafula ezikhona, ngakho-ke silungile. Qaphela ukuthi ukhiye wangaphandle u- Author_ID uxhumanisa le tafula kutafula le-AUTHORS ngokusebenzisa ukhiye wayo oyinhloko Author_ID . Sakha ubuhlobo ukugwema ukuthembela okuguquguqukayo, umklamo oyinhloko wezinqolobane zokuxhumana.
Ithebula le-AUTHORS :
- Umbhali_ID → Umbhali: Umbhali uncike ku- Author_ID .
- Umbhali → Umbhali_Nationality: Ubuzwe bungenqunywa umbhali.
- Umbhali_ID → Umbhali_Nationality: Ubuzwe bungathathwa kusuka ku- Author_ID ngombono woMlobi . Sisekhona ukuthembela okuguquguqukayo.
Sidinga ukungeza ithebula lesithathu ukuze silungise le datha:
IZWE
| Country_ID | Izwe |
|---|---|
| I-Coun_001 | I-united states |
| I-Coun_002 | Canada |
AUTHORS
| Umbhali_ID | Umbhali | Country_ID |
|---|---|---|
| Auth_001 | I-Orson Scott Card | I-Coun_001 |
| Auth_002 | UMargaret Atwood | I-Coun_002 |
Manje sinamatafula amathathu, sisebenzisa izikhiya zangaphandle zokuxhumanisa phakathi kwamatafula:
- Isihluthulelo sangaphandle setafula se-BOOK Umbhali_ID uxhumanisa incwadi kumbhali wethebula le-AUTHORS.
- Ikhi elingaphandle langaphandle lethebula le- AUTHORS Country_ID lixhumanisa umbhali ezweni elibheke etafuleni laseCOUNTRIES .
- Ithebula le-COUNTRIES alikho ukhiye wangaphandle ngoba ayinaso isidingo sokuxhumanisa nelinye itafula kule design.
Kungani Ukuthembela Okuguquguqukayo Kuyi-Database Design Design
Iyini ukubaluleka kokugwema ukuxhomeka okuguquguqukayo ukusiza ukuqinisekisa i-3NF? Ake sicabangele ithebula lethu lokuqala futhi sibone izinkinga ezakhayo:
AUTHORS
| Umbhali_ID | Umbhali | Ibhuku | Umbhali_Nationality |
|---|---|---|---|
| Auth_001 | I-Orson Scott Card | I-Ender's Game | I-united states |
| Auth_001 | I-Orson Scott Card | Izingane Zengqondo | I-united states |
| Auth_002 | UMargaret Atwood | I-Tale's Handmaid's Tale | Canada |
Loluhlobo lokuklama lungabangela ukuhlukana kwedatha nokungahambisani, isibonelo:
- Uma ususe lezi zincwadi ezimbili "Izingane Zengqondo" ne "Ender's Game," uzosusa umbhali "i-Orson Scott Card" nobuzwe bakhe ngokuphelele ku-database.
- Awukwazi ukwengeza umbhali omusha ku-database ngaphandle kokuthi wengeze nencwadi; kuthiwani uma umbhali engakashicilelwa noma ungazi igama lencwadi ayibhalile?
- Uma "i-Orson Scott Card" ishintsha ubuzwe bayo, kuzodingeka uyiguqule kuwo wonke amarekhodi abonakala kuwo. Ukuba namarekhodi amaningi nomlobi ofanayo kungabangela idatha engalungile: kuthiwani uma umuntu wokungena kwedatha engaqapheli ukuthi kukhona amarekhodi amaningi kuye futhi ashintsha idatha kwirekhodi elilodwa kuphela?
- Awukwazi ukususa incwadi efana ne "I-Tale's Handmaid's Tale" ngaphandle kokususa ngokuphelele umbhali.
Lezi zizathu ezimbalwa zokuthi kungani ukujwayelekile , nokugwema ukuxhomeka okuguquguqukayo, ukuvikela idatha nokuqinisekisa ukuvumelana.