Kudzorera Dhiyabhorosi Kubva Matafura Akawanda SQL Inner Joins

Mukati unobatanidza ruzivo rwekudzoka runowanikwa mune mbiri kana kupfuura

Kubatana kwemukati ndiko kushandiswa kunowanzoshandiswa muSQL. Vanodzoka chete ruzivo ruripo mumatafura maviri kana akawanda ema database. Icho chibatanidzwa chekubatana chinosarudza kuti ndeyepi zvinyorwa zvakabatanidzwa pamwe chete uye zvinotsanangurwa muQUERE WHERE. Semuenzaniso, kana iwe uchida runyora wevatyairi / motokari matchup umo motokari nemutyairi aripo muguta rimwechete, siri ye SQL inotevera inoita basa iri:

SELECT lastname, firstname, tag FROM drivers, motokari PANE vatyairi.location = motokari.kuendesa

Heano mhinduro yacho:

name name tag
----------- ------------ ----
Baker Roland H122JM
Smythe Michael D824HA
Smythe Michael P091YF
Jacobs Abraham J291QR
Jacobs Abraham L990MT

Cherechedza kuti migumisiro ndiyo chaiyo yakatsvakwa. Zvinogona kupfuurira kunatsiridza mhinduro kuburikidza nekutsanangurira zviyero zvinowanikwa muQUERE WHERE. Funga kuti mubvunzo wepakutanga unobatanidza vatyairi kune motokari dzavasina kubvumirwa kutyaira (vanodhairi vemotokari kumotokari uye pamwe chete). Iwe unogona kushandisa mhinduro inotevera yekugadzirisa dambudziko iri:

SELECT lastname, firstname, tag, cars.class KUBVA kunevanodzvinyirira, motokari WHERE vatyairi.location = motokari.kugadzirisa nevanotya.class = motokari.class

Muenzaniso uyu unotsanangura tafura yezvakanaka zvechikwata chekirasi muchikamu cheSELECT nokuti kirasi inonyatsonaka-inowanikwa mumatafura maviri. Nhamba yacho inowanzotsanangurira kuti tafura yefurafura inofanira kuiswa mumigumisiro yemubvunzo. Muchiitiko ichi, hazviiti misiyano, sezvo mapuranga akafanana uye anobatanidzwa achishandisa equijoin. Zvisinei, kana zvinyorwa izvi zvine dhiyamusi yakasiyana, izvi zvakasiyana-siyana zvingave zvakakosha. Heino mhinduro dzemubvunzo uyu:

zita rekutanga rematambi
---------- ------------ ---- ------
Baker Roland H122JM Car
Smythe Michael D824HA Truck
Jacobs Abraham J291QR Car

Mitsara inoshayikwa yakawirirana naMichael Smythe kumotokari uye Abraham Jacobs kuenda kune imwe motokari, motokari dzavasina kubvumirwa kutyaira.

Iwe unogonawo kushandisa majoka emukati kuti uyananise data kubva pamatafura matatu kana kupfuura .