"Imigibe" DML-Team Update MySQL

Wonke umdwelisi nkqubo, owaba ukusebenza oovimba, senze i DML-abaqhubi (yaguqulelwa isuka IsiNgesi - .. "Data Language ukuxhaphaza"), ezifana Khetha, Faka, Cima yaye Update. I SQL yam-izithuthi usebenzisa isixhobo kwayo yonke imiyalelo ngasentla.

Ezi ngxelo zibizwa ukuthetha malunga nokuqeshwa kwakhe - iirekhodi yokukhetha, ufake omtsha, nokuhlaziya iinkcukacha ezikhoyo, ngokupheleleyo, okanye ngokungqinelana nemiqathango ecaciswe, ukususwa iinkcukacha kwiziko ledatha. Izixhobo zoqeqesho ithiyori ichazwe ngokweenkcukacha siseko ukusebenza umyalelo ngamnye nolwamagama abo, kodwa akukho wafumana ukubhekisela iingxaki ezinokuvela kusenziwa ngexesha ukusetyenziswa. Loo maza ayakusoloko abambelele kule ingqalelo ezinye zazo.

Ngokufutshane malunga DML-Iingxelo (Faka)

Ngaphambi kokuqhubeka ngakumbi, kuyimfuneko kwakhona ukukhumbula iinkcukacha ezingakumbi malunga nenjongo umsebenzi ngamnye. Siya kuba abaqhubi ezimbini abanomdla ngokweenkcukacha: Faka yaye Update, kuba ixhomekeka kuzo kuveliswe iingxaki eziphambili phambili izixa ezikhulu ze data.

Kufuneka uqale nge Faka umyalelo, yaye emva koko nyukela kancinci ukuya Update. inkqubo I SQL yam, njengayo nayiphi na database mihla, sebenzisa i Faka umsebenzi ukongeza iirekhodi ezintsha ekhoyo iitafile zesiseko sedata. Syntax yalo msebenzi lulula kakhulu kwaye gca. Iqulethe udweliso kwamabala eya kwenziwa kumaxabiso, kuyo - igama kwetafile - yaye ngoko nangoko waqalisa uludwe lwe data. Ngalo lonke ixesha enze Faka database ziya kuhlaziywa kunye amaxabiso amatsha.

ingxelo Update

Noko ke, xa kusenziwa, ngokufuthi kukho iimeko ukuba ezinye iseti lwe data omnye okanye iinqobo ngaphezulu attribute ukuvuselelwa. Ngokomzekelo, imeko apho le nkampani kwaxhamla ngokutsha ngakumbi kumasebe eziphambili. Kule meko kuyimfuneko ukwenza utshintsho zesebe ngalinye. If ukutshintsha kuphela igama, ngoko ngxaki ingasombululwa ngokukhawuleza kakhulu. Noko ke, ukuba ukutshintsha ikhowudi kwicandelo ngalinye zemveliso yonke, leyo ngokuqhelekileyo lisebenza iqhosha, oko kukuthi, leyo, kubandakanya iinguqulelo ulwazi kunye ngomqeshwa ngamnye.

Update - DML-umsebenzisi linokusetyenziswa ukusombulula le ngxaki. iseva MySQL-, ezisebenzayo kunye nenani elikhulu entries, encediswa statement uhlaziyo, ukuphumeza loo umbuzo eziyimfuneko ukusombulula le ngxaki. Kodwa maxa wambi kwenzeka ngexesha lohlaziyo ayikho kwacaca kwaye kunzima ukucacisa ubuxhakaxhaka. Yiloo nto ebangela ubunzima kweerekhodi yahlaziywa, kuya kuxoxwa ngakumbi.

Yintoni omncinane sele wathi imfundiso ...

Update Team, njengoko kuchaziwe ngentla, kusetyenziswa ukuhlaziya iirekhodi ezikhoyo kule theyibhile. Kodwa practice, abaxhasi abafikelela abancedisi database azisoloko kwaziwa, kukho iseti ethile lwe data kwi tafile okanye hayi. Zamalungiselelo khangela ukufumaneka i data kwisiseko sedata ngenxa nokuhlaziya elandelayo iziphumo ixesha elininzi kunye nenkunkuma lomncedisi ubunakho.

Ukuze uphephe oku, kwisakhiwo ekhethekileyo database I SQL yam - Insert * Update, apho faka okanye uhlaziyo iya kwenziwa ngokuzimeleyo ngalinye enye. Oko kukuthi xa theyibhile ingezantsi ungeno ukuba imeko ethile, iya kuhlaziywa. Ukuba iimeko ingqalelo, i-data aliyi kufunyanwa, I SQL yam-server uyakwazi ukwenza ukulayisha data isicelo.

data Update xa kukho okuphindwe

Izakhi ebalulekileyo yale Faka - sicelo kwi SQL yam inkqubo yolawulo ledatha - «On kokuphindwe kabini Key Update» isimaphambili. Syntax epheleleyo yombuzo limi ngolu hlobo: «ufake kwi test_table (employer_id, igama) amaxabiso ( 1, 'abramov') kwi duplicate iqhosha uhlaziyo last_modified = NGOKU (); ".

Isicelo esinjalo kufuneka kusetyenziselwa ukurekhoda kumanyathelo, umzekelo, amisele ixesha kuhlangana isicatshulwa lweshishini elandelwa ngokubala ixesha lokuphumla kunye ubhaqo kokulibazisa. Ukuze ukuba ukwenza itheyibhile iingxelo ezimbalwa, ngokwaneleyo ukuba umqeshwa ngamnye ukugcina iirekhodi kunye nokuhlaziya rhoqo. It is a uyilo check duplicate ikuvumela oko.

Eneneni iingxaki ...

Ukuqwalasela lo mzekelo ungentla ubhaliso abasebenzi amanyathelo emnyango, njengoko ingxaki ukusetyenziswa samouvelichivayuschihsya (auto _ ukwenyuselwa) amasimi, apho ezisetyenziswa ukuvala amaxabiso iqhosha (primary _ key). Ukuba usebenzisa I SQL yam Update umyalelo kuyilo ne Faka auto _ kokupha, intsimi uhlala kuyanda.

Ngokufanayo, yonke into eyenzekayo xa usebenzisa ukwakhiwa replacement xa ubhaqo duplicate. "Ubhaqo-ukwenyuselwa" ixabiso yaligqiba nkqu kwimeko apho ayifuneki kuyo. Ngenxa yoku, iingxaki kuvela amaxabiso yokupasa ukuphuphuma okanye kuyehla, nto leyo ekugqibeleni kukhokelela kakuhle kweenkqubo zolawulo ledatha.

Inokuba ngxaki

Uchaza ngxaki kufuneka ingqalelo Web-ababhekisi phambili, njengoko ixhaphake kakhulu kwiinkqubo multi-umsebenzisi (websites, iiphothali, njalo njalo. P.), Xa nkqubo uyabulawa inani elikhulu kweenkqubo Faka kwaye Vuselela MySQL.

PHP - isibheno isiseko rhoqo eyenziwa. Ngoko ke, ukuba ukufezekisa imida eliphezulu, ichazwa njenge auto_increment, kwenzeka ngokukhawuleza, kwaye ekuhlalutyeni kobunzima ukuseka izizathu nje ngeke isebenze.

Ngako oko, kukhuthazwa abaphuhlisi ukuba mazilibazele ukusetyenziswa yoyilo kwi isitshixo phindo xa uhlaziyo umyalelo mysql. khetha - imibuzo xa ungena umncedisi database ziya kusebenza ngaphandle isiphoso, kodwa kongezwe iirekhodi ezintsha database izaliswe iimeko ezingentle kukukhokela elizayo kwiingxaki ezinzulu. Kungenjalo, kucetyiswa ukuba amasimi auto-ukwenyuselwa ekuqaleni ukukhangela iirekhodi zabo, uze uyibambe kubo kuhlaziywa.