Mutauro Wemagariro Akarongeka uri shure kweEll Modern Relational Databases
The Structured Query Language (SQL) ndiro mutauro wezvinyorwa. Zvose zvemazuva ano zvinyorwa zvemashoko , kusanganisira Access, FileMaker Pro, Microsoft SQL Server uye Oracle vanoshandisa SQL sevakavakwa. Ichokwadi, kazhinji ndiyo nzira chete yekuti iwe unogona kushamwaridzana ne database iyo pachayo. Zvose zvinoshandiswa mumashandisirwo emashandisirwo anopa mazita anopa kuwanikwa kwemashoko uye kushandiswa kwekushandura hazvisi chinhu kunze kwevashanduri veSQL. Vanotora zviito zvaunoita zvakajeka uye unozvishandura ku SQL mirairo inonzwisiswa ne database.
SQL yakafanana neChirungu
Panguva ino, iwe unogona kunge uri kufunga kuti hausi wezvigadziri uye unodzidza chirongwa chekugadzirira hazvikwanisi kumusoro kwako. Nenzira yakanaka, pamusana wayo, SQL iri rurimi ruri nyore. Iine nhamba shoma yemirairo, uye mirairo iyo inonyatsoverengwa uye inenge yakarongeka sechirevo cheChirungu.
Kuzivisa Databases
Kuti uchinzwisise SQL, zvinokosha kuti uve nekunzwisisa kwekunyanya kwekuti mabhuku anonyatsoshanda sei. Kana iwe uchinetseka nemashoko akaita se "tafura," "ukama," uye "mubvunzo," unzwe wakasununguka kurima mberi! Kana zvisingaiti, iwe unogona kuda kuverenga nheyo yeDashatimendi yeZvimbiso zvisati zvaenderera mberi.
Ngatitarisei muenzaniso. Ngatiti iwe une database yakagadziriswa yakagadzirirwa kuchengetedza zvinyorwa zvechitoro chakanaka. Imwe yematafura ari mu database yako inogona kuva nemitengo yezvinhu zviri pamashefuti ako akanyorwa nendima dzakasiyana dzemaoko dzinoona chimwe nechimwe chinhu. Iwe ungangodaro waipa iyo tafura zita risiri se "Mitengo."
Zvichida iwe unoda kubvisa zvinhu kubva muchitoro chako zvinotengeswa kupfuura $ 25, iwe "waizotsvaga" dhesi yezita rezvinhu izvi zvose. Ndiyo apo SQL inopinda.
Your First SQL Query
Tisati tapinda mutemo weSQL unoda kuwana ruzivo urwu, ngatiedzei kupindura mubvunzo wedu mubasa reChirungu. Tinoda "kusarudza nhamba dzose dzezvitoro kubva pamatengo emvura apo mutengo uri kupfuura $ 25." Icho chikumbiro chakanaka kana chichirondedzerwa muchiChirungu chisinganzwisisiki, uye chinenge chiri nyore muSQL. Heino mutsara wakafanana weSQL:
Sarudza StockNumber
FROM FROM Price
PANE PANO> 5
Zviri nyore sezvakadaro! Kana ukaverenga chirevo chiri pamusoro apa, uchaona kuti yakanyanya kufanana nemubvunzo weChirungu watakabvunza mundima yekupedzisira.
Kududzira SQL Zvinyorwa
Iye zvino ngativei imwe muenzaniso. Nguva ino, zvisinei, tichazozviita shure. Chokutanga, ndichakupa sumo yeSQL uye rega tione kana iwe uchigona kutsanangura iri muChirungu Chinyorwa:
Sarudza Mutengo
FROM FROM Price
WHERE StockNumber = 3006
Saka iwe unofunga kuti chirevo ichi chinyi? Ndizvo chaizvo, inowana mutengo kubva kune dhesi yezvinhu 3006.
Pane imwe chidzidzo chakarerurika iwe waunofanira kutora kubva pakurukura kwedu pane ino: SQL yakafanana neChirungu. Usanetseka nezvekuti unovaka sei zvinyorwa zveSQL; isu tichasvika kune iyo mune dzimwe dzose dzenyaya dzedu. Ingoziva kuti SQL haisi iyo inotyisa sezvo inogona kutanga kuonekwa.
The Range of SQL Statements
SQL inopa zvakasiyana-siyana zvemashoko, ayo CHISINGO chimwe chete. Heano mimwe mimwe mienzaniso yezvirevo zveSQL dzakawanda:
- SQL INSERT uye SQL DONESA: Inoshandisa kana kubvisa zvinyorwa kubva patafura
- SQL UPINDA: Kuchinja marekodhi ari patafura
- SQL DZAI uye SQL DROP: Inoita kana inobvisa tafura
Mukuwedzera kune izvi zvinyorwa zveSQL, unogona kushandisa zvikamu zveSQL, pakati pavo chirevo che WHERE chinoshandiswa mumitambo yapfuura. Zvinyorwa izvi zvinoshandiswa kuchenesa rudzi rwe data kuti zviite. Mukuwedzera kune WHERE clause, heano mamwe magwaro anowanzoshandiswa-anoshandiswa:
- NESU kana OR: Sungai mitemo yakawanda kuti mugadzirise sarudzo yeSQL
- KUNA: Kufananidza kukosha kune maitiro akadaro uchishandisa wildcard
- GADZIRWA NEZVO: Inoshandisa data mukukwira kana kuburuka kurongeka
Kana iwe uchida kuenderera mberi nekuongorora SQL, SQL Fundamentals inodzidzisa zvikamu zvakawanda zvinotsvaga zvikamu nezvikamu zveSQL zvakadzama.