Nhanganyaya kuDhadharo Relationships

Izwi re "database" kana kuti "ukama" rinotsanangura nzira iyo data iri mumatafura yakabatana.

Vatsva kunyika yenhoroondo vanowanzoomerwa kuona musiyano pakati pe database neparashiriti. Vanoona mahwendefa e data uye vanoziva kuti databases inokubvumira kuronga nekutsvaga dhidhiro nenzira itsva, asi vanokundikana kunzwisisa kukosha kwehukama pakati pe data inopa teknolojia yekodzero dzekodzero zita racho.

Ukama hunokubvumira kurondedzera kushamwaridzana pakati pezvinyorwa zvakasiyana-siyana mumatafura nenzira dzakasimba. Izvi hukama hunokwanisa kubva huchitsvaga kuti uite simba rine mutsara-tafura, inozivikanwa sejoins.

Mitauro yeDatabase Relationships

Kune zvitatu zvakasiyana-siyana zvehutano hwehutano, imwe neimwe inodanwa maererano nenhamba yematafura ezvingabatanidzwa muhukama. Chimwe chezvinhu izvi zvitatu zveukama chiripo pakati pematafura maviri.

• Imwe-kune-imwe hukama hunoitika apo imwe neimwe inopinda mufurafura yekutanga ine imwe chete, uye imwe chete, mumwe wega mutafura yechipiri. Imwe-kune-imwe hukama haisati yashandiswa nokuti inowanzova yakanyatsobudirira kungoisa zvese zvayo mutafura imwechete. Vamwe vanogadzirisa dhivhesiti vanoshandisa ruzivo urwu hukama kuburikidza nekugadzira matafura ane subset ye data kubva kune imwe tafura.
• Imwe-kune-vazhinji hukama ndihwo hukama hunowanikwa hwehutano hwepa database. Zvinowanzoitika kana imwe nhoroondo iri muTebhu A inofanirwa kune imwe kana zvimwe zvinyorwa muTebhi B, asi imwe nhoroondo muTebheti B inofananidzwa nekodha imwe chete muTepa A. Somuenzaniso, ukama pakati peTeresi yeVadzidzisi neVadzidzi vanofura mune imwe yepuraimari database ingangodaro iine ukama kune mumwe chete kune vakawanda, nokuti mudzidzi mumwe nomumwe ane mudzidzisi mumwe chete, asi mudzidzisi mumwe nomumwe ane vadzidzi vakawanda. Iyi-kune-yakawanda yakagadzirisa inobatsira kubvisa deta yakawanda.

• Zvakawanda-kune-vakawanda hukama hunoitika kana imwe nhoroondo iri muTebhu A inofanirwa kune imwe kana zvinyorwa zvakawanda muTebhi B, uye imwe nhoroondo muTebheti B inofananidzwa neimwe kana zvinyorwa zviri muTepa A. Somuenzaniso, ukama huri pakati peVadzidzisi neDzidzo tafura inogona kuva yakawanda-kune-vazhinji nokuti mudzidzisi mumwe nomumwe anogona kurayira zvinopfuura imwechete, uye imwe neimwe yefundo inogona kuva nevadzidzisi vakawanda.

Kuzvitsvakurudza Kuwirirana: Nyaya Inokosha

Kuzvitsvakurudza kwehukama hukama hunoitika kana pane tafura imwe chete inobatanidzwa. Chimwe chimiro chinozivikanwa ndeye Vashandi vefurafura ine ruzivo pamusoro pomukuru wevashandi vose. Mutariri wega wega ndiye mushandi uye ane mutevedzeri wake. Muchiitiko ichi, kune humwe-kune-mazhinji humwe hutano hwehukama, sezvo mushandi wega wega ane mutariri mumwe chete, asi mutariri mumwe nomumwe angave ane vashandi vakawanda.

Kuumba Ukama Nenzira Dzekunze

Iwe unogadzira ukama pakati pematafura nekutsanangura kiyi yekunze . Izvi zvinotaurira dhipatimendi rehukama kuti matafura acho akabatana sei. Mune zviitiko zvakawanda, imwe chinyorwa muTebhu A rine zvigaro zvekutanga zvinotaurwa kubva muTebhiri B.

Chimbofunga zvakare muenzaniso weVadzidzisi neVadzidzi. Tafura yeVadzidzisi ine chinyorwa chete, zita, uye chikamu chetsika:

Vadzidzi vanoverenga tavo inosanganisira ID, zita, uye chinyorwa chekune imwe nyika:

Nheyo Mudzidzisi_FK muDafura yeVadzidzi inotaura nezvekukosha kwekukosha kwemurayiridzi muTeresi yeVadzidzisi.

Kazhinji, vashandi vekudhina vanozoshandisa "PK" kana kuti "FK" muzita rekhomu kuti vaone nyore nyore kiyi yepakutanga kana yekunze yekona.

Cherechedza kuti aya mabwendefa maviri anoratidza hukama-kune-mazhinji pakati pevadzidzisi nevadzidzi.

Ukama uye Kuratidza Kuvimbika

Kana ukangowedzera kiyi yekunze patafura, unogona kugadzira zvinyorwa zvepamusoro zvepamusoro izvo zvinosimbisa kutaridzika kwakakwana pakati pematafura maviri. Izvi zvinoita kuti hukama pakati pematafura hurambe husingachinji. Apo imwe tafura ine chinyorwa chekune dzimwe nyika kune imwe tafura, pfungwa yekutsanangurira kutendeseka inotaura kuti chero ipi zvayo yekunze inokosha muTebhu B inofanira kureva pane imwe yereyo iri muTebvu A.

Kutevedzera Ukama

Zvichienderana newaini yako yepamusoro, unoshandisa hukama pakati pematafura nenzira dzakasiyana. Microsoft Access inopa wizard iyo inokubvumira nyore nyore kuti ubatanise tafura uye kuti uitewo kuti uonekwe kwakakwana.

Kana iwe uri kunyora SQL zvakananga, iwe unotanga kuumba tafura yeVadzidzisi, kuzivisa chidimbu cheDhiyabhorosi kuti chive chinokosha chikuru:

DENGA TABLE Teachers (

InstructorID INT AUTO_INCREMENT CHINHU CHINYANYA,
Mudzidzisi_Name VARCHAR (100),
Nzira VARCHAR (100)
);

Apo iwe unogadzira Vadzidzi patafura, iwe unotaura kuti murairidzi weMufundisi_FK uve chinyorwa chekune dzimwe nyika kurondedzera iyo InstructorID column in the Teachers 'table:

DZENGA TABLE Vadzidzi (
Mudzidzisi IN INTO_INCREMENT PRIMARY KEY,
Mudzidzi_Name VARCHAR (100), Teacher_FK INT,
VANHU VEMUNYORI (Teacher_FK) REFERENCES Teachers (InstructorID))
);

Kushandisa Ukama Kuti Ubatane Tables

Kana ukangodaro wakasika hukama kana humwe hwehutano muhitsuwa rako, unokwanisa kushandisa simba rawo kuburikidza uchishandisa mibvunzo ye SQL JOIN kuyananisa mashoko kubva pamatafura akawanda. Rudzi rwakajairika rwekubatanidza ndeye SQL INNER JOIN, kana kubatana nyore. Icho chikwata chekubatana chinodzorera zvose zvinyorwa zvinosangana nemamiriro ekubatana kubva pamatafura akawanda. Semuenzaniso, ichi CHIMWE chiitiko chichadzorera Mudzidzi_Name, Teacher_Name, uye Nzira apo chitubu chekunze muVadzidzi vanofananidza chinonyanya kukosha muTeresi yeVadzidzisi:

Sarudza Vadzidzi.Student_Name, VadzidzisiTeacher_Name, Teachers.Course
KUBVA KUVadzidzi
INNER JOIN Vadzidzisi
KUVadzidzi.Teacher_FK = Teachers.InstructorID;

Uyu mazwi anopa tafura chimwe chinhu chakadai:

Dzokera Kudzoka kubva kuSQL Join Statement

Mudzidzi_NameTeacher_NameCourseLowell SmithJohn DoeEnglishBrian ShortJohn DoeEnglishCorky MendezJane SchmoeMathMonica JonesJohn DoeEnglish