Kudzokorora Data Ne SQL Mibvunzo: Kuzivisa SETI Statement

Mutauro wakagadziridzwa unopa vashandisi vepa database zvakasimba uye zvakanyatsogadziriswa zvekutsvaga tsanangudzo yemagetsi - ICHITATU CHECHIKAMU. Muchikamu chino, tichatarisa fomu yakawanda yeSETEMO chirevo uye kunyora shanduro shomanana yedhesi dzemibvunzo pamwechete. Kana ichi chiri chekutanga chekubhadharwa munyika yeChirongwa Chekutsvakurudza Mutauro, unogona kuda kuongorora sarudzo yeSQL Fundamentals vasati vaenderera mberi.

Kana uri kutarisa kugadzira imwe nhepfenyuro itsva kubva pakutanga, nyaya yekusika Databases uye Mathesi muSQL inofanira kuratidza yakanaka kuruka-off point.

Iye zvino zvawakanyanyisa pamusoro pezvinyorwa, ngatitangei kutsvaga kweshoko reCHOKUTA. Sezvakaitwa nezvikoro zveSQL zvekare, ticharamba tichishandisa zvinyorwa zvinowirirana neAnSI SQL yakawanda. Iwe unogona kuda kutarisa zvinyorwa zveDBMS yako kuti uone kana inotsigira zvakasarudzwa zvingaita zvingagonesa kushanda uye / kana kubudirira kweSQL yako code.

The General Form of the SELECT Statement

Iko maitiro akawandisa eCHITEMO CHECHOKARA inooneka pasi apa:

Sarudza select_list
KUBVA kubva kunzvimbo
WHI chiitiko (s)
GROUP BY expression
KUVA nechiitiko
ITA NOKUDZIDZA

Mutsara wekutanga wechitauriri unotaurira SQL pro processor kuti uyu murairo iCHITATIDZO chekutsvaga uye kuti tinoda kutora mashoko kubva kune database. I- select_list inotibvumira kuti titaure rudzi rwemashoko atinoda kutora.

The FROM clause mumutsara wechipiri inotsanangura mahwendefa ezvinyorwa (database) akangobatanidzwa uye WHERE clause inotipa simba rekugadzirisa migumisiro kune avo vanonyora kuti vanosangana nemamiriro ezvinhu akadaro . Zvitatu zvitatu zvekupedzisira zvinomiririra zvinhu zvakaderera kunze kwehuwandu hwechinyorwa ichi - tichazovatsvaga mune ramangwana SQL zvinyorwa.

Nzira iri nyore yekudzidza SQL ndeyomuenzaniso. Tine izvozvo mupfungwa, ngatitangei kutarisa pane imwe mibvunzo yepa database. Munyaya ino yose, tichashandisa tafura yevashandi kubva kune fungidzira XYZ Corporation databases revanhu rekushandisa kuti tifananidze mibvunzo yedu yese. Heino tafura yose:

Kudzorera Itafura Yose

XYZ Corporation Mutevedzeri weHuman Resources inogamuchira mushumo wegore negore unopa ruzivo rwekubhadhara uye ruzivo kune umwe neumwe mushandi wekambani. Chizvarwa chemugumo uyu muenzaniso weSENET statement chimiro chakanaka. Iyo inongowana chete mashoko ose ari mukati mefurafura yepa database - mutsara wega uye mutsara mumwe nomumwe. Heino mhinduro ichaita izvi:

SELECT *
KUBVA vashandi

Yakananga, yakarurama? I-asteriski (*) inowanikwa mu- select_list ndeye wildcard inoshandiswa kuzivisa dhesi rekuti tinoda kutora mashoko kubva kune dzimwe misoro mutafura yevashandi inowanikwa muCHITSA CHOKUTANGA . Taida kuwana mashoko ose mu database, saka zvakanga zvisina kukodzera kushandiswa izwi re WHERE kuti rive nemiganhu yakasarudzwa kubva patafura.

Hezvino izvo zvatinotsvaga mhinduro dzedu zvinoita se: