I SQL yam - umbuzo kulo mbuzo. I SQL yam: imizekelo umbuzo. imibuzo MySQL eveze

Okwangoku, umntu ngamnye kufuneka bagcine ukukhula ngokukhawuleza ulwazi yedijithali. Yaye ekubeni inkoliso le ngcaciso ibaluleke, kuyimfuneko ukuba kulondolozwe ngokupheleleyo ngendlela yedijithali ukuze zisetyenziswe kwixesha elizayo. Kule meko, isicelo ubuchwepheshe bale mihla ezifana zolwazi. Bona zinika yokugcina oluthembekileyo naluphi digital ulwazi kunye nedata ufikelelo ingenziwa nangaliphi na indawo ehlabathini. Enye iiteknoloji ngaphantsi ingqalelo yinkqubo ye SQL yam zolwazi.

DBMS I SQL yam - yintoni na le nto?

A zonxulumelwano Inkqubo yolawulo ledatha I SQL yam yenye iiteknoloji zokugcina ithandwa kakhulu kwaye zisetyenziswa ngokuqhelekileyo. kusebenziso bongamile ngandlela ezininzi database okhoyo. Ngokukodwa, omnye iimpawu eziphambili kukukwazi ukusebenzisa imibuzo engoma I SQL.

Ngoko ke, uninzi lweeprojekthi, apho ixesha kubalulekile kwaye kuyimfuneko ukuqinisekisa ukugcinwa iinkcukacha zomsebenzi, kwakunye ukwenza iisampulu nkcukacha ziyaphuhliswa kwiziko ledatha I SQL. Inkoliso yezi meko yenza websites. Kulo mzekelo, I SQL yam esikhuthazwa ekuphunyezweni zombini (blog, website, amakhadi oshishino njalo njalo. P.) ezincinane Yaye iingxaki kunokuba enkulu (shopping online, ukugcinwa data , njalo njalo. D.). Kuzo zombini ezi meko, umboniso iinkcukacha kwiphepha le web ezazisetyenziswa I SQL yam-umbuzo. Isicelo yabakhi ngokuzama ukwenza izinto ezininzi amathuba okunikelwe Management Planning System.

kufuneka ihlelwe njani yokugcina

Kuba yokugcina lula kunye nokusebenza kwe-data odolwe ngokuyimfuneko. Ubume data ukujonga itafile tlakukeke, ezo zisetyenziswa ukugcina ulwazi ngayo. iitafile zesiseko sedata i iseti amasimi (columns) esihambelanayo indawo nganye ezithile into data.

Umzekelo, ukuba itafile abasebenzi kwinkampani ethile, oko isakhiwo kakhulu elula kuya kuba ngolu hlobo lulandelayo. Kuba umsebenzi ngamnye unique number, nto leyo ngokuqhelekileyo isetyenziswe iqhosha etafileni apha. Kwandula ke itafile zibhalwe data nabasebenzi. Kusenokuba nantoni: Igama elipheleleyo, inombolo yekhadi, kuba kuso esiqingqiweyo, yomnxeba, idilesi kunye nezinye iinkcukacha. Ngokutsho kwiimfuno ukuzinza (6 iintlobo eqhelekileyo-lwazi) kwakunye for I SQL yam-imibuzo emgceni fields yakhiwe le itafile kufuneka atomic, oko kukuthi, hayi ukuba enumerations okanye uluhlu. Ngoko ke, ngokuqhelekileyo, itafile, kukho amasimi ezahlukeneyo ngegama lokugqibela, igama lokuqala, njalo-njalo. D.

Ngasentla ngumzekelo engenamsebenzi lobume itafile ledatha. Nangona kunjalo, akukho ukuhlangabezana ngokupheleleyo iimfuno ebalulekileyo ukuzinza nangoku. Xa iinkqubo real, idala i amacandelo itafile olongezelelweyo. Ngoko ke, le theyibhile ilandelayo endaweni yamagama "iSebe" umhlathi kufuneka siqulathe kumasebe.

Njani na isampuli data

Ukuze kuvunjululwe idata esuka neetafile kwinkqubo yolawulo ledatha I SQL yam, iqela elikhethekileyo - Khetha umbuzo. Kumncedisi ledatha awasabela ngokuchanekileyo isibheno, isicelo kufuneka kakuhle kuyilwa. isakhiwo Umbuzo wenziwe ngolu hlobo. Nayiphi ukufikelela kumncedisi database iqala elingundoqo khetha. Kwaba naye wakha zonke imibuzo MySQL. Imizekelo zingaba yokuntsonkotha ezahlukeneyo, kodwa lo mgaqo zokwakha elifana kakhulu.

Kufuneka ukhankanye Fields ufuna ukukhetha ulwazi olufunayo. Libala amasimi kokudlula kwi isiphumlisi emva macebiso khetha. Xa onke amacandelo afunekayo sele idwelisiwe isicelo lixela into itafile apho isampuli kuya kwenzeka ngoncedo iingcebiso kwaye ucacise igama itafile.

Kuba imida isampuli kwi SQL yam-imibuzo ezidityaniswe abasebenzisi ezizodwa, ngaphandle database. Kuba isampuli unduplicated (unique) data esetyenziswa yitsho ezahlukahlukeneyo, kwaye ukubeka iimeko - umqhubi apho. Ngokomzekelo esebenzayo theyibhile ingentla, siya kuqwalasela isicelo befuna ulwazi Igama abasebenzi abasebenza kwisebe "Sales". isakhiwo Umbuzo kuthatha uhlobo njengoko kule theyibhile ingezantsi.

Ingcamango umbuzo ekwiseli

Kodwa ke inkalo ephambili ye-database, njengoko kuchaziwe apha ngasentla, ukukwazi ukujongana lilungiswe imibuzo I SQL. Kufuneka ibukeke? Ukusuka igama kuba sobala waqonda ukuba lo isicelo eyenziwe emigangatho izicelo ezimbini okanye ngaphezulu. Ngethiyori, ngokufunda awohluke sedata kuthiwa I SQL yam ayithi simele inani I SQL yam-imibuzo ezinokuthi ifakwe kwi umbuzo engundoqo. Noko ke, unako uzihlole xa befundisa, baze baqinisekise ukuba emva elishumi ekwiseli umbuzo ixesha lokuphendula okwesibini ukwandisa nzulu. Enoba kwenzeka ntoni na, xa kusenziwa kukho iingxaki ezifuna ukuba usebenzise entsonkothileyo kakhulu SQL yam-umbuzo. Isicelo angafuna ezona 3-5 wokwehla ekwiseli.

Ukwakhiwa imibuzo ekwiseli

Ekuhlalutyeni ulwazi efundiweyo, ingasetyenziswa iqela lemibuzo malunga apho sub-imibuzo, uze xa ukwazi ukusombulula ingxaki yokwahlula zibe elula ngaphandle nzima isakhiwo. Ukuziqhelisa, sub-imibuzo zisetyenziswa ukusombulula iingxaki ezintsonkothileyo. uhlobo olunjalo iingxaki iimeko xa akwaziwa kwangaphambili iimeko apho umda silixabisile isampulu ngakumbi ziya kwenzeka. Akwenzeki ukuba ukusombulula iingxaki ezinjalo, ukuba usebenzisa nje rhoqo I SQL yam-umbuzo. Xa isicelo, equlathe uluhlu, aya kuba izithintelo search zingatshintsha ngokuhamba kwexesha okanye kwangaphambili nga kuzichaza.

Ukuba sicinga theyibhile ingentla, umzekelo lulandelayo umsebenzi onzima. Masithi kufuneka sazi inkcazelo esisiseko malunga abaqeshwa abo aphantsi Grishina Grigoriya Grigorevicha, ngubani na ke intloko kwentengiso. Xa uyila umbuzo asazi inombolo yalo yesazisi. Ngoko ekuqaleni simele sazi oko. Lisebenzisa umbuzo elula ukuba uya kufumana imigaqo engundoqo yesigqibo kwaye kuya kukhuthaza engundoqo I SQL yam-umbuzo. Isicelo ibonisa ngokucacileyo ukuba subquery ufumana inombolo yesazisi umsebenzi, nto leyo ichaza ngakumbi kumda yombuzo engundoqo:

Kulo mzekelo, naliphi na icebiso isetyenziselwa ukukhusela kunokwenzeka ukuba iimpazamo, ukuba abasebenzi nee-inishiyali ezinjalo ziya kuba mbalwa.

iziphumo

Ukushwankathela, kufanele kuqatshelwe ukuba kukho ezinye izinto ezongezelelweyo ezininzi eziququzelela kakhulu ukwakhiwa umbuzo, njengoko DBMS I SQL - isixhobo esinamandla uluhlu olubanzi lwezixhobo ukugcinwa kunye processing.