Gwema ukuxhomekeka koTshintsho lokuNcedisa ukuQinisekisa ukuQinisekisa
Ukuxhomekeka kokutshintshela kwidatha kukuxhamlana ngqo phakathi kwexabiso kwitafile enye edala ukuxhomekeka kokusebenza . Ukufezekisa umgangatho oqhelekileyo weFom yeSithathu eQheleleyo (3NF), kufuneka uchithe naluphi na ukuxhomekeka kokutshintsha.
Ngokwemvelo yalo, ukuxhomekeka okutshintshileyo kudinga iimpawu ezintathu okanye ngaphezulu (okanye iikholomu zeenkcukacha) ezinokuxhomekeka komsebenzi phakathi kwabo, oku kuthetha ukuba ikholomu A etafileni incike kwiKholam B ngeColumn.
Makhe sibone indlela oku kusebenza ngayo.
Isibonelo sokuxhomekeka koTshintsho
ABASEBENZI
| Author_ID | Umbhali | Incwadi | Umbhali_Nationality |
|---|---|---|---|
| Auth_001 | Orson Scott Card | Umdlalo we-Ender | eunited States |
| Auth_001 | Orson Scott Card | Umdlalo we-Ender | eunited States |
| Auth_002 | UMargaret Atwood | I-Tale's Handmaid's Tale | Khanada |
KUMzekelo WABASEBENZI:
- Incwadi → Umbhali : Nantsi, umxholo weNcwadi ubeka uphawu lweMbhali . Ukuba uyazi igama lencwadi, ungafunda igama lomlobi. Nangona kunjalo, uMbhali akayi kugqiba iNcwadi , kuba umbhali angabhala iincwadi ezininzi. Ngokomzekelo, ngenxa yokuba siyazi igama lomlobi u-Orson Scott Card, asikwazi igama lencwadi.
- Umbhali → Umbhali_Nobomi : Ngokufanayo, umxholo weMbhali ubeka uMongameli_Nationality , kodwa ayikho enye indlela ejikeleze; ngenxa yokuba siyazi ukuba ubuzwe asisho ukuba sinokumisela umbhali.
Kodwa le tafile ibonisa ukuxhomekeka okutshintshayo:
- Incwadi → Umbhali_Nationality: Ukuba siyazi igama lencwadi, sinokukwazi ukucacisa ubuzwe ngekholamu yoMlobi.
Ukuphepha ukuxhomekeka koTshintsho
Ukuqinisekisa ifomu leSithathu eliqhelekileyo, masisuse ukuxhomekeka kokutshintsha.
Singaqala ngokususa ikholomu yeNcwadi kwitafile zabaMlawuli kunye nokudala itafile yeencwadi ezihlukeneyo:
IINCWADI
| Book_ID | Incwadi | Author_ID |
|---|---|---|
| Book_001 | Umdlalo we-Ender | Auth_001 |
| Book_001 | Abantwana beNgqondo | Auth_001 |
| Book_002 | I-Tale's Handmaid's Tale | Auth_002 |
ABASEBENZI
| Author_ID | Umbhali | Umbhali_Nationality |
|---|---|---|
| Auth_001 | Orson Scott Card | eunited States |
| Auth_002 | UMargaret Atwood | Khanada |
Ngaba oku kukulungiselele? Makhe sihlolisise ukuxhomekeka kwethu ngoku:
IBHAYIBHELI :
- Book_ID → Incwadi: Incwadi incike kwi- Book_ID .
- Azikho ezinye izixhomekeke kuletafile ezikhoyo, ngoko sikulungele. Qaphela ukuba ukhiye wangaphandle u- Author_ID udibanisa le tafile kwitafile ze- AUTHORS ngokubaluleka kwinqununu yaloMlawuli_ID . Siye sakha ubudlelwane ukuze sigweme ukuxhomekeka kokutshintsha, inkcazelo ebalulekileyo yeenkcukacha zolwazi.
Itafile :
- Umbhali_ID → Umbhali: Umbhali uncike kwi- Author_ID .
- Umbhali → Umbhali_Nationality: Ubuzwe bunokumiselwa ngumlobi.
- Umbhali_ID → Umbhali_Nationality: Ubuzwe bunokumiselwa kwi- Author_ID ngokusebenzisa umxholo weMbhali . Sisenokuxhomekeka kokutshintsha.
Kufuneka songeze itafile yesithathu ukulungelelanisa le datha:
AMAHLA
| Country_ID | Izwe |
|---|---|
| Coun_001 | eunited States |
| Coun_002 | Khanada |
ABASEBENZI
| Author_ID | Umbhali | Country_ID |
|---|---|---|
| Auth_001 | Orson Scott Card | Coun_001 |
| Auth_002 | UMargaret Atwood | Coun_002 |
Ngoku sineetafile ezintathu, sisebenzisa izitshixo zangaphandle zokudibanisa phakathi kweetafile:
- ISIXHUMA sephepha lokungaphandle kwetafula uMlawuli_ID udibanisa incwadi kumbhali kwitheyibhile le-AUTHORS.
- Ikhonkco langaphandle letafula le-AUTORS Country_ID idibanisa umlobi kwilizwe etafuleni laseCOUNTRIES.
- Itheyibhile yelizwe alikho ikona yangaphandle kuba ayinaso isidingo sokuqhagamshela kwelinye itafile kulo mbhalo.
Kutheni Kutheni Ukuxhomekeka Kwezitshintshi Ziyingozi Imveliso Yedatha
Yiyiphi ixabiso lokuphepha ukuxhomekeka okutshintshileyo ukunceda ukuqinisekisa i-3NF? Makhe sihlolisise itafile yethu yokuqala kwaye sibone imiba eyenzayo:
ABASEBENZI
| Author_ID | Umbhali | Incwadi | Umbhali_Nationality |
|---|---|---|---|
| Auth_001 | Orson Scott Card | Umdlalo we-Ender | eunited States |
| Auth_001 | Orson Scott Card | Abantwana beNgqondo | eunited States |
| Auth_002 | UMargaret Atwood | I-Tale's Handmaid's Tale | Khanada |
Olu hlobo loyilo lunokufaka isandla kwiimpazamo zeenkcukacha kunye nokungahambelani, umzekelo:
- Ukuba ususile iincwadi ezimbini "Abantwana Bengqondo" kunye ne "Ender's Game," uya kususa umlobi "Orson Scott Card" kunye nobuzwe bakhe ngokupheleleyo kwi-database.
- Awunakongeza umbhali omtsha kwi database ngaphandle kokuba ungeze incwadi; kuthekani ukuba umbhali akakashicilelwa okanye awuyazi igama lencwadi ebhalileyo?
- Ukuba "i-Orson Scott Card" yatshintsha ubumi bayo, kufuneka uguqulwe kuzo zonke iirekodi ezibonakala kuyo. Ukuba namarekhodi amaninzi kunye nombhali omnye unokubangela ukuba kubekho idatha engalungile: kuthekani ukuba umntu ongena kwi-data akaqapheli ukuba kukho iirekodi ezininzi kwaye utshintshe idatha kwirekhodi elilodwa kuphela?
- Awukwazi ukususa incwadi efana ne "Tale's Handmaid's Tale" ngaphandle kokususa ngokupheleleyo umbhali.
Ezi zizathu ezithile zokuba kulungelelaniso , kwaye kugweme ukuxhomekeka kokutshintsha, ukukhusela idatha kunye nokuqinisekisa ukuhambelana.