Pakati SQL: Zitsanzo Kufotokozera

Pamene tikugwira ntchito ndi Nawonso achichepere ubale umene deta awasungira matebulo Intaneti nthawi zambiri anakumana ndi ntchito zitsanzo zosankhidwazi mfundo m'gulu (palibepo) mu uthunthu wina. chilankhulo SQL limakupatsani kuthandauza angapo, amene ayenera (sayenera) a mtengo wa options osiyana - woyendetsa Mu ngati woyendetsa, osakaniza zinthu zambiri - zochepa, komanso SQL kwa Pakati woyendetsa. Kufotokozera ndi zitsanzo m'nkhani ino tikambirana pa Baibulo posachedwapa.

"Pakati" woyendetsa mu SQL: malembedwe zoletsa

Kwenikweni woyendetsa pakati SQL ndipo anamasulira - "pakati". ntchito zake limachititsa anapereka malire "ndiponso ku" munda makamaka, ndipo ngati phindu lotsatira imagwera mkati osiyanasiyana, ndiye mkhalidwe adzakhazikitsidwa kuti "Woona" ndi phindu adzaphedwa chitsanzo chomaliza.

The malembedwe a woyendetsa ndi losavuta kwambiri:

Monga mukuonera, pambuyo nfundo yaikhulu pakati muyenera mwachindunji kufunika kwa malire m'munsi, ndiye NDI, ndi malire chapamwamba.

Ati, mtundu wa deta woyendetsa akhoza ntchito pakati SQL:

1. Ndi manambala - inteja ndi fractional.
2. Ndi zipatso.
3. Ndi malemba.

Kodi pakati SQL mawu ali peculiarities ena. Ife kuwadziwa:

1. Pamene akugwira ntchito manambala ndi madeti a makhalidwe malire "ndiponso ku" ali m'gulu la chitsanzo.
2. mtengo osiyanasiyana m'munsi ayenera kukhala osachepera malire chapamwamba, mwinamwake palibe kanthu kuwonetsedwa, chifukwa chikhalidwe ndi sitinganenenso woona. kusamalidwa ayenera kukhala, pamene, mmalo mwa makhalidwe abwino achindunji chikhalidwe zosintha zina.

Pamene ntchito ndi mtengo lemba la osiyanasiyana chapamwamba sikuphatikizidwa mu chitsanzo, ngati si kumatanthauza molondola kwambiri. Tikambirana mbali mu zigawo izi mwatsatanetsatane.

Zitsanzo manambala ndi madeti osiyanasiyana ena

Gome ndi Ngopambana deta ntchito mu bungwe. Tebulo adzakhala ndi kapangidwe zotsatirazi:

Lembani mu tebulo ndi deta zotsatirazi:

Kupanga SQL kafufuzidwe pakati, zomwe zingatithandize kusankha ogwira ntchito onse amene ali ndi 2 kapena 3 ana:

Ndipo zotsatira zake zidzakhala mizere itatu deta ndi antchito ndi mayina Shumilin, Tropnikov ndi Avdeeva.

Tsopano kusankha ogwira ntchito analandira 1 January 2005 31 December 2016. Tikumbukenso kuti zinasokoneza makompyuta osiyana m'njira zosiyanasiyana amakulolani kuti alembe mawu a masiku. Nthawi zambiri, tsiku la mphamvu ku mawonekedwe tsiku ndi umodzi chaka (kapena yabwino) ndipo zinalembedwa mu makoti umodzi kapena iwiri. The DBMS MS Access tsiku akupanga chizindikiro "#". Thamangani chitsanzo zachokera chabe kuti:

Ndipo zotsatira zake zidzakhala ogwira ntchito asanu alemba ntchito panthawi palimodzi.

Tiyeni tiwone momwe ntchito pakati zingwe SQL.

Ntchito pakati zingwe

A vuto sizachilendo omwe ayenera kuthetsedwa pamene ntchito ndi mayina a ogwira ntchito - ndi kufunika kusankha yekha iwo amene maina kuyamba ndi kalata ena. Ndipo timayesetsa adzapha kafufuzidwe ndipo sankhani ogwira ntchito maina kuyamba ndi dzina lapitali A kwa B:

Chotsatira motere:

Monga mukuonera, antchito awiri ndi dzina la pa kalata B mu mndandanda sanali m'gulu. Chifukwa chiyani? Ndipotu ndendende mmene woyendetsa akuyerekeza zingwe kutalika wosiyana. Line "B" ndi lalifupi chingwe "Vinogradov" ndi padded. Koma pamene kusanja Potengela Zilembo mipata adzakhala mofulumira otchulidwa ndi dzina la chitsanzo sangagwere. zinasokoneza makompyuta osiyana kupereka njira zosiyanasiyana kuti athetse vutoli, koma nthawi zambiri chophweka njira kusonyeza kudalirika kwa kalata wotsatira wa zilembo mu osiyanasiyana:

Pamene anaphedwa, chifukwa kafufuzidwe osangalala ife kwathunthu.

nuance kulipo kokha pamene ntchito deta ndi khalidwe, koma zimasonyeza kuti ngakhale pamene akugwira ntchito monga akuti pakati, muyenera kukhala osamala.