Qoba ho itšetleha ka mekhoa ea ho fetoha ho thusa ho netefatsa ho tloaeleha
Ho itšetleha ka mokhoa o fetohang ka boitsebiso bo itseng boemong bo sa tobang bo pakeng tsa litekanyetso ho tafoleng e le 'ngoe e bakang ho itšetleha ka mokhoa o sebetsang . E le hore u finyelle tekanyetso e tloaelehileng ea Foromo ea Boraro e Tloaelehileng (3NF), u tlameha ho felisa botšepehi bofe kapa bofe.
Ka tlhaho ea eona, ho itšetleha ka ho fetela ho hloka litšobotsi tse tharo kapa ho feta (kapa li-column) tse nang le tšebelisano e sebetsang pakeng tsa bona, e bolelang hore Khoeli ea A ka tafoleng e itšetlehile ka Moqhomo B ho feta Column C.
A re boneng hore na sena se ka sebetsa joang.
Mohlala oa Tšepo ea ho Fetoha
BANGATA
| Mongoli_ID | Mongoli | Buka | Mongoli_Nationality |
|---|---|---|---|
| Auth_001 | Orson Scott Card | Game ea Ender | United States |
| Auth_001 | Orson Scott Card | Game ea Ender | United States |
| Auth_002 | Margaret Atwood | Tale ea Mesebetsi | Canada |
Mohlala oa BANGATA holimo:
- Buka → Mongoli : Mona, tšobotsi ea Buka e beha tšobotsi ea Mongoli . Haeba u tseba lebitso la buka, u ka ithuta lebitso la moemeli. Leha ho le joalo, Mongoli ha a khetholle Buka , hobane mongoli a ka ngola libuka tse ngata. Ka mohlala, feela hobane re tseba lebitso la mongoli Orson Scott Card, ha re tsebe lebitso la buka.
- Mongoli → Mongoli_Nationality : Ka tsela e tsoanang, tšobotsi ea Mongoli e khetholla Mongoli_Nationality , empa eseng ka tsela e 'ngoe ho potoloha; hobane feela re tseba sechaba ha se bolele hore re ka tseba hore na mongoli ke mang.
Empa tafole ena e qala ho itšetleha ka mokhoa o fetohang:
- Buka → Author_Nationality: Haeba re tseba lebitso la buka, re ka tseba hore na sechaba ke sa mofuta ofe ka Mongolo oa Mongolo.
Ho qoba ho itšetleha ka ho fetoha
E le ho netefatsa hore Tlhaho ea Boraro e Tloaelehileng, a re tlose botšepehi bo feteletseng.
Re ka qala ka ho tlosa khoeli ea Buka ho tafoleng ea Bangoli le ho theha tafole ea Libuka tse fapaneng:
BUKA
| Book_ID | Buka | Mongoli_ID |
|---|---|---|
| Book_001 | Game ea Ender | Auth_001 |
| Book_001 | Bana ba Kelello | Auth_001 |
| Book_002 | Tale ea Mesebetsi | Auth_002 |
BANGATA
| Mongoli_ID | Mongoli | Mongoli_Nationality |
|---|---|---|
| Auth_001 | Orson Scott Card | United States |
| Auth_002 | Margaret Atwood | Canada |
Na see se se lokisitse? A re ke re hlahlobe litšepiso tsa rona hona joale:
BUKA :
- Book_ID → Buka: Buka e itšetlehile ka Buka_ID .
- Ha ho na litšepiso tse ling tse teng tafoleng ena, ka hona re lokile. Hlokomela hore senotlolo sa linaheng tse ling Author_ID e kopanya tafole ena tafoleng ea AUTHORS ka senotlolo sa eona sa mantlha Author_ID . Re bōpile kamano ho qoba ho itšetleha ka mokhoa o fetohang, phetoho ea bohlokoa ea lits'ebeletso tsa marang-rang.
Tafole ea bahloli :
- Author_ID → Mongoli: Mongoli o itšetlehile ka Mongoli_ID .
- Mongoli → Mongoli_Nationality: Sechaba se ka khethoa ke mongoli.
- Mongoli_ID → Mongoli_Nationality: Sechaba se ka khethoa ho tloha ho Author_ID ho latela tšobotsi ea Mongoli . Re ntse re e-na le botumo ba ho fetoha.
Re hloka ho eketsa tafole ea boraro ho tloaelella dintlha tsena:
LITABA
| Country_ID | Naha |
|---|---|
| Coun_001 | United States |
| Coun_002 | Canada |
BANGATA
| Mongoli_ID | Mongoli | Country_ID |
|---|---|---|
| Auth_001 | Orson Scott Card | Coun_001 |
| Auth_002 | Margaret Atwood | Coun_002 |
Hona joale re na le litafole tse tharo, re sebelisa lisebelisoa tsa linaha tse ling tsa ho kopanya pakeng tsa litafole:
- Sehlooho sa kantle ho tafole ea Buka ea Book_ID e amahanya buka ho mohlophisi tafoleng ea AUTHORS.
- Letšoao la kantle la tafole ea AUTHORS Country_ID e ama mongoli ho ea naheng tafoleng ea COUNTRIES.
- Tafole ea COUNTRA ha e na senotlolo sa kantle ho naha kaha ha e hlokehe ho hokahanya le tafole e 'ngoe moqapong ona.
Ke hobane'ng ha ho itšetleha ka ho fetoha ha lintho ho fetohile se sebe?
Bohlokoa ba ho qoba ho itšetleha ka lintho tse feteletseng ho thusa ho netefatsa hore na 3NF ke eng? A re nahaneng ka tafole ea rona ea pele hape 'me re bone mathata ao e bakang:
BANGATA
| Mongoli_ID | Mongoli | Buka | Mongoli_Nationality |
|---|---|---|---|
| Auth_001 | Orson Scott Card | Game ea Ender | United States |
| Auth_001 | Orson Scott Card | Bana ba Kelello | United States |
| Auth_002 | Margaret Atwood | Tale ea Mesebetsi | Canada |
Mofuta ona oa moralo o ka kenya letsoho litabeng tsa boitšoaro le ho se lumellane, mohlala:
- Haeba u tlose libuka tse peli tsa "Bana ba Kelello" le "Ender's Game," u tla tlosa mongoli "Orson Scott Card" le bochaba ba hae ka ho feletseng ho basebetsi.
- U ke ke ua eketsa mongoli e mocha database hafeela u eketsa buka; ho thoe'ng haeba mongoli a ntse a sa phatlalatsoe kapa u sa tsebe lebitso la buka eo ae ngotseng?
- Haeba "Orson Scott Card" e fetohile moahi oa naha, o tla tlameha ho e fetola litlalehong tsohle tseo a li hlahelang. Ho ba le litlaleho tse ngata le mongoli a le mong ho ka fella ka boitsebiso bo sa nepahalang: ho thoe'ng haeba motho ea kenang data a sa hlokomele hore na ho na le litlaleho tse ngata ho eena le ho fetola data ka tlaleho e le 'ngoe feela?
- Ha o khone ho hlakola buka e kang "Tale ea Mesebetsi" ntle le ho tlosa mongoli ka ho feletseng.
Tsena ke mabaka a mang feela a etsang hore ho be le maemo a tloaelehileng , le ho qoba ho itšetleha ka lintho tse fetohang, ho sireletsa dintlha le ho netefatsa hore o tsitsitse