Language Structured Query (SQL) ndi ndondomeko ya malangizo ogwiritsidwa ntchito polumikizana ndi deta yolumikizana . Ndipotu, SQL ndilololo lokha limene malemba ambiri amamvetsetsa. Nthawi zonse mutagwirizanako ndi database, pulogalamuyi imasulira malamulo anu (kaya ali ndi ndondomeko zamagulu kapena zolembera) mu SQL mawu omwe database ikudziwa kutanthauzira. SQL ili ndi zigawo zikuluzikulu zitatu: Chiyankhulo cha Deta (DML), Chidziwitso cha Deta (DDL), ndi Language Control Language (DCL).
Ntchito Zowoneka za SQL pa Webusaiti
Monga wogwiritsa ntchito pulojekiti iliyonse yamagetsi, mumagwiritsa ntchito SQL, ngakhale simukudziwa. Mwachitsanzo, tsamba la webusaiti yogwira ntchito (monga mawebusaiti ambiri) limagwiritsa ntchito mauthenga kuchokera pa mafomu ndikusinthasintha ndikugwiritsira ntchito kulembetsa funso la SQL lomwe limatulutsanso uthenga kuchokera ku deta yomwe ikufunika kuti ipangire tsamba lotsatira lotsatira.
Taganizirani chitsanzo cha mndandanda wamakono pa intaneti ndi ntchito yofufuza. Tsamba lofufuzira lingakhale ndi mawonekedwe omwe ali ndi bokosi lolembamo limene mumalowetsa kafukufuku ndikusindikiza batani. Mukasindikiza batani, seva ya intaneti imapezekanso zolemba zonse kuchokera kuzinthu zamakono zomwe zili ndi nthawi yosaka ndipo zimagwiritsa ntchito zotsatira kuti zikhale ndi tsamba lapafupi pafunso lanu.
Mwachitsanzo, ngati mukufunafuna mankhwala omwe ali ndi "Irish," seva ikhoza kugwiritsa ntchito mawu otsatirawa a SQL kuti mupeze zinthu zokhudzana nazo:
Kutanthauziridwa, lamulo ili likutenga zolemba zilizonse kuchokera ku tebulo lachinsinsi lomwe limatchedwa "mankhwala" omwe ali ndi malembo "osasimbika" paliponse mkati mwa dzina la mankhwala.
Chiyankhulo cha Deta Chilankhulo
Chilankhulo Chogwiritsira Ntchito (DML) chiri ndi gawo la malamulo a SQL omwe amagwiritsidwa ntchito kawirikawiri - omwe amangogwiritsira ntchito zomwe zili mu deta mwa njira ina. Malamulo anayi omwe amapezeka kwambiri pa DML amachotsa chidziwitso kuchokera ku lamulo lachinsinsi (SELECT), onjezerani chidziwitso chatsopano ku (database), musinthe zinthu zomwe zikusungidwa mumasamba (lamulo la UPDATE), ndikuchotsani zambiri kuchokera ku database ( DUTANI lamulo).
Chiyankhulo cha Deta
Chilankhulo cha Deta (DDL) chili ndi malamulo omwe sagwiritsidwe ntchito mobwerezabwereza. Malamulo a DDL amasintha ndondomeko yeniyeni ya database, osati zomwe zili m'mabuku. Zitsanzo za malamulo a DDL omwe amagwiritsidwa ntchito kawirikawiri ndi omwe amagwiritsidwa ntchito popanga tebulo latsopano (CREATE TABLE), kusintha kapangidwe ka tebulo lachinsinsi (ALTER TABLE), ndi kuchotsa tebulo lachinsinsi (DROP TABLE).
Chilankhulo Chogwiritsa Ntchito Deta
Chilankhulo Chogwiritsa Ntchito Deta (DCL) chikugwiritsidwa ntchito poyendetsa makasitomala opezeka pazolumikizi . Icho chimapangidwa ndi malamulo awiri: lamulo la GRANT, lomwe limagwiritsidwa ntchito kuwonjezera zivomezi za malo ogwiritsira ntchito, ndi lamulo la REVOKE, lomwe limachotsedwa kuchotsa zilolezo zomwe zilipo. Malamulo awiri awa ndiwo maziko a ofesi yachidziwitso.
Makhalidwe a SQL Lamulo
Mwamwayi kwa ife omwe sali mapulogalamu a pakompyuta, malamulo a SQL apangidwa kuti akhale ndi syntax yofanana ndi Chingerezi. Kawirikawiri amayamba ndi ndondomeko ya lamulo yomwe ikufotokoza zoyenera kuchita, zotsatiridwa ndi ndime yomwe imalongosola cholinga cha lamulo (monga tebulo yomwe ili mkati mwa deta yomwe ikukhudzidwa ndi lamulo) ndipo potsiriza, ndime zina zomwe zimapereka malangizo ena.
Kawirikawiri, kungowerenga mawu a SQL mokweza kukupatsani lingaliro labwino la zomwe lamulo likufuna kuti lichite. Tengani kamphindi kuti muwerenge chitsanzo ichi cha mawu a SQL:
Kodi mukuganiza kuti mawu awa adzachita chiyani? Amaphatikizapo tebulo la ophunzira la deta ndikuchotsa zolemba zonse za ophunzira omwe anamaliza maphunziro awo mu 2014.
Kuphunzira SQL Programming
Takhala tikuyang'ana zitsanzo zingapo zosavuta za SQL m'nkhani ino, koma SQL ndi chinenero chachikulu komanso champhamvu. Kuti mumve zambiri mwatsatanetsatane, onani SQL Fundamentals .