Pulogalamu Yoyesedwa Yokonzedwa ndi Dongosolo Lomwe Zonse Zamakono Zogwirizana
Language Structured Query (SQL) ndi chilankhulo cha zidziwitso. Zosintha zamakono zamakono, kuphatikizapo Access, FileMaker Pro, Microsoft SQL Server ndi Oracle ntchito SQL monga maziko awo omanga. Ndipotu nthawi zambiri ndi njira yokha yomwe mungagwiritsire ntchito ndi deta. Mapulogalamu onse ogwiritsira ntchito omwe amapereka deta ndi ntchito zowonongeka sizoposa otembenuza SQL. Amatenga zochita zomwe mumazichita ndikuzimasulira ku malamulo a SQL omwe amamvetsetsa.
SQL ilifanana ndi English
Panthawiyi, ukhoza kuganiza kuti siwe wolemba mapulogalamu ndi kuphunzira chinenero chokonzekera ndizomwe simukudziwa bwino. Mwamwayi, pamutu wake, SQL ndi chinenero chophweka. Lili ndi malamulo angapo, ndipo malamulowa amawoneka kwambiri ndipo ali pafupi kupanga monga ziganizo za Chingerezi.
Kutsegulira Zosungidwa
Kuti mumvetse SQL, nkofunika kukhala ndi chidziwitso chofunikira cha momwe ziwonetsero zimagwirira ntchito. Ngati mumakhala ndi mawu monga "tebulo," "chiyanjano," ndi "funso," mukhale omasuka kulima patsogolo! Ngati simukufuna, mungafune kuwerengera zomwe Zinalembedwa Zina Zomwe Zidasinthidwe musanasunthe .
Tiyeni tione chitsanzo. Tiyerekeze kuti muli ndi deta yosungiramo zinthu zosungiramo zosungiramo sitolo yabwino. Mmodzi mwa matebulo omwe ali mumasitomala anu akhoza kukhala ndi mitengo ya zinthu pa masamulo anu omwe amawerengedwa ndi nambala zachinsinsi zomwe zimadziwika chinthu chilichonse. Mwinamwake mungapereke tebuloli dzina losavuta ngati "Mitengo."
Mwinamwake mukufuna kuchotsa zinthu mu sitolo yanu zomwe zili mtengo woposa $ 25, "mufunse" mndandanda wa mndandanda wa zinthu zonsezi. Izi ndi pamene SQL imalowa.
SQL Yanu Yoyamba Funso
Tisanalowe ku SQL mawu oti tipeze chidziwitso ichi, tiyeni tiyesere kufotokoza funso lathu momveka bwino. Tikufuna "kusankha nambala zonse za malonda kuchokera pa tebulo mitengo yomwe mtengo uli pa $ 25." Ndilo pempho labwino kwambiri pamene likufotokozedwa mu Chingerezi chosavuta, ndipo ndilosavuta ku SQL. Pano pali mawu ofanana a SQL:
Sankhani StockNumber
Kuchokera ku mitengo
PAMENE mtengo> 5
Ndi zophweka ngati zimenezo! Ngati muwerenga mawuwa pamwamba mokweza, mudzapeza kuti ndi ofanana kwambiri ndi funso la Chingerezi lomwe talifunsa m'ndime yotsiriza.
Kutanthauzira Mafotokozedwe a SQL
Tsopano tiyeni tiyesere chitsanzo china. Nthawi ino, komabe, tidzazichita kumbuyo. Choyamba, ndikupatsani chiganizo cha SQL ndipo tiwone ngati mungathe kufotokoza momveka bwino Chingelezi:
SANKANI Mtengo
Kuchokera ku mitengo
PAMENE StockNumber = 3006
Kotero, kodi mukuganiza kuti mawu awa akuchita chiyani? Ndiko kulondola, imapeza mtengo kuchokera ku deta ya katundu 3006.
Pali phunziro limodzi losavuta limene muyenera kuchotsa pa zokambirana zathu pa mfundo iyi: SQL ili ngati Chingerezi. Osadandaula za momwe mumapangira mawu a SQL; ife tidzafika ku izo mu zotsalira zathu zonse. Dziwani kuti SQL siopseza ngati ingayambe kuonekera.
Mndandanda wa Mafotokozedwe a SQL
SQL imapereka mauthenga osiyanasiyana, omwe CHISANU ndi chimodzi. Nazi zitsanzo za mafotokozedwe ena a SQL ambiri:
- SQL INSERT ndi SQL DELETE: Kuika kapena kuchotsa mbiri kuchokera pa tebulo
- SQL KWAMBIRI: Kusintha malemba mu tebulo
- SQL Pangani ndi SQL DROP: Kupanga kapena kuchotsa tebulo
Kuwonjezera pa mawu awa a SQL, mungagwiritse ntchito zigawo za SQL, pakati pawo NDIME yeniyeni yomwe imagwiritsidwa ntchito mu zitsanzo zapitazo. Malemba awa amatsimikizira mtundu wa deta kuti agwirepo. Kuphatikiza pa CHIFUKWA CHAKE pamenepa, pali ziganizo zina zomwe amagwiritsidwa ntchito:
- NDIPO kapena OR: Gwirizanitsani zinthu zambiri kuti musinthe ndemanga ya SQL
- YAM'MBUYO YOTSATIRA MITU YA NKHANI YAM'MBUYO YOTSATIRA MITU YA NKHANI
- ZOKHALA: Ikani ma data akukwera kapena kutsika
Ngati mukufuna kudziwa zambiri za SQL, SQL Fundamentals ndi maphunziro ambiri omwe amafufuza zigawo ndi mbali za SQL mwatsatanetsatane.