"Izingibe Zokufihla Ukuthi" DML-Team Update MySQL

Njalo uMklami, okwadingeka ukuba sisebenze yolwazi, sibhekene DML-opharetha (kusuka esiNgisini - .. "Idatha Izikhundla Ulimi"), ezifana Khetha, Faka, Susa futhi Buyekeza. MySQL-ezokuthutha futhi isebenzisa arsenal yayo yonke imiyalo ngenhla.

Le nkulumo ngokunengqondo ukhuluma ngani bakhe aphoyintimenti - amarekhodi ukukhetha, ukufaka ukwamukela izindinganiso ezintsha, ubuyekeza imininingwane ekhona, ephelele, noma ngokuhambisana nemibandela ebekiwe, ukususwa ulwazi egciniwe. I theory zokuqeqesha zichazwe ngokuningiliziwe isimiso yokusebenza umyalo ngamunye bese-syntax yabo, kodwa akukho lapho kutholakala izinkomba ubunzima ayeyobhekana lungase luvele umkhuba ngesikhathi ukusetshenziswa. Lokhu kwaziswa uzobe anikelwe kuhlolwe ezinye zazo.

Kafushane mayelana DML-izitatimende (Faka)

Ngaphambi kokuqhubeka okwengeziwe, kubalulekile waphinda bakhumbule imininingwane okwengeziwe ngenjongo umsebenzi ngamunye. Sizoba opharetha amabili nesithakazelo kabanzi: Faka futhi Isibuyekezo, ngoba incike kuwo athola ubunzima abhekene main ekucubunguleni esiningi idatha.

Kufanele uqale Shutheka umyalo, bese kancane kancane bathuthele Update. MySQL uhlelo, njenganoma iyiphi enye semininingwane yesimanje, sebenzisa operation Faka ukwengeza amarekhodi entsha ekhona amatafula database. I-syntax lo msebenzi ilula kakhulu futhi kuqondile. Liqukethe uhlu Amasimu okuyinto zizokwenziwa amagugu, lapho uya khona - igama etafuleni - futhi ngokushesha kwethulwa uhlu idatha. Ngaso sonke isikhathi uma enze database Faka kuzobuyekezwa amanani entsha.

Buyekeza isitatimende

Nokho, umkhuba, kaningi kunezimo ezingahlanganisiwe kwabanye iqoqo idatha elilodwa noma ngaphezulu ngemfanelo amanani olusha. Njengoba isibonelo, esimweni lapho inkampani kabusha nge ukuqanjwa kabusha eminye iminyango main. Kulokhu-ke kubalulekile ukuba wenze ushintsho emnyangweni ngamunye. Uma kuphela ushintsha igama, inkinga ke zingaxazululwa ngokushesha okukhulu. Nokho, uma kushintshwa esephepheni of ingxenye yonke ukukhiqizwa, ngokuvamile ukhonza njengoba ukhiye oyihloko, okungukuthi ngamunye, esikhundleni salokho, luhambisana nomthwalo izinguquko ulwazi futhi umsebenzi ngamunye.

Buyekeza - DML-opharetha singasetshenziswa ukuxazulula le nkinga. iseva MySQL-, ezisebenza nge inqwaba okufakiwe, ngosizo isitatimende buyekeza, akhiphe nombuzo edingekayo ukuxazulula le nkinga. Kodwa ngezinye izikhathi kwenzeka ngesikhathi ubuyekeza akukalungi kahle kucace futhi kubukhuni ukulichaza eyinkimbinkimbi. Yilokho kubangela ubunzima kwamarekhodi olusha, Kuzoxoxwa.

Yini okuncane lokushiwo nakwetfulwa theory ...

Buyekeza Team, njengoba kuphawulwe ngenhla, asetshenziselwa ukubuyekeza amarekhodi akhona ethebuleni. Kodwa umkhuba, amaklayenti ufinyelela amaseva semininingwane Awaziwa njalo, kukhona ezithile idatha kumathebula noma cha. Olwandulelayo uhlole ubukhona idatha ku database ukuze Ukuvuselela okwalandela kwemiphumela isikhathi esiningi futhi bachitha iseva samandla.

Ukuze ugweme lokhu, e database MySQL isakhiwo ekhethekile - Faka * Update, lapho faka noma buyekeza engenziwa ngayodwana. Yilapho-ke etafuleni sinokufakwa ngoba isimo esithile, kuzobuyekezwa. Uma izimo kubhekwe, idatha ngeke butholakale, MySQL-iseva uyakwazi ukwenza ukulayisha idatha isicelo.

Buyekeza idatha lapho ziyimpinda

Ebalulekile lokhu Faka - isicelo MySQL Ukuphathwa semininingwane uhlelo - «On ompindakabili Key Update» Isiqalo. I-syntax ephelele nombuzo simiswe ngalendlela lelandzelako: «ufake test_table (employer_id, igama) namanani ( 1 'abramov') ku impinda ukhiye buyekeza LAST_MODIFIED = MANJE (); ".

Isicelo esinjalo lingasetshenziswa ukurekhoda izenzo, isibonelo, ukucacisa empambana ndima ibhizinisi isikhathi kulandelwa ekubaleni isikhathi sokuphumula kanye ukuthola ukubambezeleka. Ukuze wenze itafula amarekhodi ambalwa, anele umsebenzi ngalinye ukuze ugcine amarekhodi Ukuvuselela njalo. Kuyinto impinda isheke design kuyivumela.

Empeleni izinkinga ...

Uma ucabangela isibonelo esingenhla nokubhaliswa abasebenzi isinyathelo emnyango, njengoba inkinga samouvelichivayuschihsya ukusetshenziswa (auto _ anyuswe) Amasimu, okuyinto zivamise esetshenziswa ukugcwalisa esiyinhloko yamanani angukhiye (primary _ ukhiye). Uma usebenzisa MySQL Buyekeza umyalo design nge Faka auto _ ukungeza, insimu njalo ziyanda.

Ngokufanayo, konke kwenzeka uma usebenzisa ukwakhiwa esikhundleni esimweni ukuthola impinda. "Ngokuzenzakalela anyuswe" Inani luyanda ngisho esimweni lapho ayidingeki. Ngenxa yalokhu, kuba nezinkinga ukuchichima pass amagugu noma ububanzi, kamuva kuholele ukungasebenzi ngabaphathi semininingwane izinhlelo.

Kungenzeka inkinga

Ichaza inkinga kumele kubhekwe Web-developers, njengoba kuvamile kakhulu izinhlelo multi-umsebenzisi (amawebhusayithi, Intanethi, nokunye. P.), Uma uhlelo uyabulawa inqwaba izinqubo Faka futhi Buyekeza MySQL.

PHP - yezikhalazo base ngokuvamile kakhulu okwenziwa. Ngakho-ke, ukuze sifinyelele eziseceleni esiphezulu, kuchazwa njenganoma auto_increment, kwenzeka ngokushesha, futhi ngo-ukuhlaziywa kobunzima ukusungula izizathu nje ngeke zisebenze.

Ngakho-ke, onjiniyela bayakhuthazwa ukuba anake ukusetshenziswa design ku ukhiye impinda e umyalo mysql update. khetha - imibuzo lapho ufinyelela leseva database izosebenza ngaphandle ngephutha, kodwa ukwengeza amarekhodi entsha database igcwele nezimo ezingajabulisi isahola esizayo abhekana nezinkinga ezinkulu. Kungenjalo, kunconywa okuzenzakalelayo anyuswe Amasimu ekuqaleni uhlole amarekhodi abo, bese unamathela kuzo olusha.