Kev Qhia Siv Siv Txuas Mus Hauv SQL rau Pawg Cov Ntaub Ntawv ntawm Ntau Yam Ntxhuav

Siv SQL Inner Joins los ua ke cov ntaub ntawv los ntawm peb lossis ntau lub rooj

Koj tuaj yeem siv SQL cov lus nqe los ua ke cov ntaub ntawv los ntawm peb lossis ntau lub rooj. SQL koom yog yooj ywm heev, thiab nws cov kev ua tau zoo siv tau los siv ua ke los ntawm ntau cov ntxhuav. Cia wb mus saib SQL statements uas tso cai rau koj muab cov kev sib tw los ntawm peb cov ntxhuav sib txawv uas siv ib qho kev sib nkag ua ke.

Sab Hauv Piv Txwv

Piv txwv, noj cov ntxhuav uas muaj cov tsav tsheb nyob rau hauv ib lub rooj thiab tsheb match-ups hauv ob. Qhov sib koom ua ke tshwm sim nyob rau qhov twg ob lub tsheb thiab tus tsav tsheb nyob hauv tib lub nroog. Lub puab sib koom xaiv tag nrho cov kab ntawm ob lub rooj sib tham uas muaj qhov sib piv ntawm txhua qhov chaw.

Cov lus hais hauv qab no yog siv cov lus qhia los ntawm cov tsav tsheb thiab cov tsheb hauv cov rooj zaum uas tus neeg tsav tsheb thiab tsheb nyob hauv tib lub nroog:

SELECT lastname, firstname, lossis LOS NTAWM tsav tsheb, tsheb twg qhov twg tsav driver.location = vehicles.location

Qhov lus nug no ua rau cov ntsiab lus nram qab no:

lastname firstname tag -------- --------- --- Saib Koj Lub Neej Zoo Tshaj Plaws Lawm Maiv Xyooj Hmong New Movie 2014

Tam sim no, ntev qhov piv txwv no kom muaj cov txheej xwm thib peb. Xav txog tias koj xav kom muaj cov tsav tsheb thiab cov tsheb nyob rau ntawm qhov chaw uas qhib rau hnub so. Koj tuaj yeem nqa tau peb qhov txheej txheem hauv koj cov lus nug los ntawm kev sib txuas lus TXOG raws li nram no:

SELECT lastname, firstname, lossis, open_weekends LOS NTAWM cov tsav tsheb, cov chaw, qhov chaw tsav tsheb.location = vehicles.location THIAB vehicles.location = location.location THIAB locations.open_weekends = 'Yog' lastname firstname tag open_weekends -------- --------- -------------- Baker Roland H122JM yog Jacobs Abraham J291QR yog Jacobs Abraham L990MT yog

No lub peev xwm txuas ntxiv mus rau theem pib SQL JOIN tsab ntawv tso cai rau koj muab cov ntaub ntawv sib sau ua ke. Ntxiv nrog rau kev sib txuas nrog lub rooj sib txoos nrog, koj tuaj yeem siv cov txheej txheem no los ua ke ntau cov ntxhuav siv ib qho kev koom nrog. Cov kev sib ntsib sab nrauv muaj cov kev tshwm sim uas muaj nyob hauv ib lub rooj, tiam sis tsis muaj qhov sib piv hauv cov lus sib tham.