Tataiso ea ho Sebelisa Maqhama a Kantle ho SQL ho Sehlopha sa Ditaba ho tswa ho Tables tse ngata

Sebelisa Maqhama a Kopano a SQL ho kopanya data ho tloha litafole tse tharo kapa ho feta

U ka sebelisa lipolelo tsa SQL JOIN ho kopanya data ho tloha litafole tse tharo kapa ho feta. SQL JOIN e feto-fetoha haholo, 'me mesebetsi ea eona e matla e ka sebelisoa ho kopanya data ho tloha litafole tse ngata. A re shebeng lipolelo tsa SQL tse u lumellang ho kopanya liphello ho tsoa litafole tse tharo tse fapaneng ho sebelisa letsoho la ka hare.

Mohlala oa ho kopanya ka hare

Ka mohlala, nka litafole tse nang le bakhanni tafoleng e le 'ngoe le lipapali tsa koloi ka bobeli. Kopano e ka hare e etsahala moo koloi le mokhanni li leng teng motseng o le mong. Kamore ea ka hare e khetha mela eohle ea litafole ka bobeli tse nang le papali e pakeng tsa li-columns tsa sebaka.

Polelo ea SQL e ka tlase e kopanya data ho tloha ho baqhobi le likoloi tsa likoloi maemong ao mokhanni le koloi ba leng teng motseng o le mong:

SELECT lastname, firstname, tag FROM HO bakhanni ba likoloi, likoloi HA HO BA bakhanni.banang = likoloi

Potso ena e hlahisa liphetho tse latelang:

Baker Roland H122JM Smythe Michael D824HA Smythe Michael P091YF Jacobs Abraham J291QR Jacobs Abraham L990MT

Hona joale, eketsa mohlala ona ho kenya tafole ea boraro. Ak'u inahanele hore o batla ho kenyelletsa bakhanni feela le likoloi tse teng libakeng tse bulehileng mafelong a beke. U ka tlisa tafoleng ea boraro tafoleng ea hau ka ho fetisetsa polelo ea JOIN ka tsela e latelang:

SELECT lastname, firstname, tag, open_weekends HO tsoa ho bakhanni, likoloi, libaka HOO ho nang le bakhanni.location = likoloi.haho ​​le likoloi.a sebaka = libaka.haho ​​le libaka.open_weekends = 'Ee' lebitso la ho qetela la lebitso la hau le le leng le le leng le le leng le le leng le le leng le le leng le le leng la ho qetela -------- --------- --- ------------- Baker Roland H122JM e le Jacobs Abraham J291QR e, Jacobs Abraham L990MT e, e

Kakaretso ena e matla ho polelo ea motheo ea SQL JOIN e u lumella ho kopanya lintlha ka tsela e rarahaneng. Ntle le ho kopanya litafole tse nang le kopano ea kahare, u ka boela ua sebelisa mokhoa ona ho kopanya litafole tse ngata ho sebelisa letsoho le ka ntle. Likarolo tse ling tse kantle li kenyeletsa liphello tse teng tafoleng e le 'ngoe empa ha li na se bapalanang le tafoleng e kopantseng.