Fumana ngakumbi malunga neMibono yeData
Iimbonari zeemboniselo zivumela ukuba lula ukunciphisa ubunzima bokuba namava omsebenzisi wokugqibela kunye nokunciphisa amandla abo okufikelela kwiinkcukacha ezifumaneka kwiitheyibhile zeenkcukacha ngokunciphisa idatha edluliselwe kumsebenzisi wokugqibela. Okubalulekileyo, imbono isebenzisa iziphumo zombuzo wesigcaziso ukuba zizalise ngokutsha izinto eziqulethwe kwitafile yedata yolwazi.
Kutheni Usebenzisa Imiboniselo?
Kukho izizathu ezibini zokubonelela abasebenzisi ukufikelela kudatha ngokusebenzisa imibono kunokuba banikeze ngokufikelela ngqo kwietafile zeenkcukacha:
- Imibono inikezela ukhuseleko olulula, oluninzi . Ungasebenzisa umbono wokukhawulela idatha umsebenzisi avunyelwe ukuyibona etafileni. Ngokomzekelo, ukuba unabasebenzi betafile kwaye unqwenela ukubonelela ngabasebenzisi abathile ukufikelela kwiirekhodi zabasebenzi bexesha elizeleyo, unokudala umbono oqulethe kuphela ezo rekhodi. Oku kulula kakhulu kunokunye (ukudala nokugcina itafile yethunzi) kwaye kuqinisekisa ukuthembeka kwengcaciso.
- Ukubona kulula ukwenza amava . Imibono yokufihla iinkcukacha eziyinkimbinkimbi zeetafile zakho zeenkcukacha ezivela kubasebenzisi bokugqibela abangenakuzibona. Ukuba umsebenzisi ulahla iziqulatho zembono, abayi kubona iikholomu zeetable ezingakhethiweyo ngombono kwaye abanako ukuqonda. Oku kubakhusela ekudidaneni okubangelwa ngamakholomu angathathi kakuhle, izihlomelo ezikhethiweyo kunye neetekisi zetekisi .
Ukudala iMboniselo
Ukudala imbono ngokucacileyo: ufuna nje ukudala umbuzo oqulethe imiqobo onqwenela ukuyinyanzelisa kwaye uyifake ngaphakathi komyalelo we-CREATE VIEW. Nantsi i syntax:
DALA IMBONO yombono we-AS
Ngokomzekelo, ukuba unqwenela ukudala abasebenzi bexesha elizeleyo ndijonge kwingxenye yangaphambili, uya kukhupha umyalelo olandelayo:
DALA IMBONO YONKE i-AS
HLOLA kuqala igama, igama_kugqibela, igama lomqeshwa
KWABASEBENZI
LAPHO isimo = 'FT'
Ukuguqula iMboniselo
Ukutshintsha iziqulatho zembono kusetyenziswa i-syntax efanayo kunye nokudala imbono, kodwa usebenzisa umyalelo we-ALTER VIEW esikhundleni somyalelo we-CREATE VIEW. Umzekelo, ukuba ufuna ukufaka isithintelo kwimbonakalo epheleleyo yongeza inombolo yomnxeba yomqeshwa kwiziphumo, uya kukhupha umyalelo olandelayo:
I-ALTER VIEW i-AS epheleleyo
HLOLA kuqala igama, igama_kugqibela, umsebenzisi_id, umnxeba
KWABASEBENZI
LAPHO isimo = 'FT'
Ukususa Umbono
Kulula ukususa umbono kwi-database usebenzisa umyalelo we-DROP VIEW. Umzekelo, ukuba unqwenela ukucima abaqeshwa besikhathi esigcwele, uya kusebenzisa umyalelo olandelayo:
JONGA VIEW ngokugcwele