Impela, nakhu okusalungiswa kokuqala kwe-athikili ephelele ye-'Drop Constraint in Oracle SQL'.
Ukwehlisa izithiyo kuthebula kusizindalwazi se-Oracle SQL kuyisici esizuzisa kakhulu konjiniyela. Lo msebenzi wenza ukuguqulwa kwesakhiwo setafula kube lula futhi kukhuphule ukusebenza kahle kolwazi olugciniwe. Ulimi lwe-SQL ngokwendabuko lusekela lesi sici, usebenzisa ukuthi, ungakwazi ukulahla izithiyo ngokushesha. Kufanele ubambe ilungelo elibalulekile le-DROP ANY TABLE ukuze igama lakho lomsebenzisi lenze lo msebenzi. Ukuqinisekisa ubuqotho besizindalwazi sakho, kubalulekile ukuthi ubuyekeze futhi ubuyekeze izithiyo ezihambisana nezidingo zohlelo lwakho lokusebenza.
ALTER TABLE table_name
DROP CONSTRAINT constraint_name;
Lo myalo olula we-Oracle SQL yi- yehlisa umkhawulo isiyalo. Lapha, 'igama_lethebula' kanye 'negama_le-constraint' yizibambi zendawo okufanele uzishintshe ufake igama lakho langempela lethebula kanye negama lokuvinjelwa ofisa ukulisusa.
Isinyathelo Ngesinyathelo Umhlahlandlela Wekhodi
Uma uthi nhlรก, ikhodi yokwehlisa izithiyo ibonakala ilula, kodwa kubalulekile ukuqonda ukusebenza kwayo.
1. ALTER ITHEBULA iwumyalo we-Oracle SQL okuvumela ukuthi uguqule ukwakheka kwethebula elikhona.
2. Okulandelayo okwakho okwangempela itafula_igama: ithebula ofisa ukususa kulo umkhawulo.
3. The DROP UKUVinjelwa isitatimende siwumyalo oyinhloko oholela ngokusebenzayo ekususweni komkhawulo ochaziwe.
4. Ekugcineni, i isibambiso_name kubonisa umkhawulo othize ofuna ususwe etafuleni lakho.
I-Oracle SQL kanye Nemitapo yolwazi yayo
I-Oracle SQL iwulimi olunamandla lokuphatha imininingwane egciniwe. Ukusebenziseka kwayo ngezindlela eziningi ekuphatheni nasekuphatheni izakhiwo zesizindalwazi kanye nedatha kuyenza ibe ithuluzi elibaluleke kakhulu konjiniyela. Futhi inemisebenzi eminingi eyakhelwe ngaphakathi kanye nemitapo yolwazi esiza ekuphatheni izinhlobo ezahlukene zedatha nokusebenza, ngaleyo ndlela andise ukusebenza kwayo.
Omunye umtapo onjalo ngu DBMS_UTILITY, iphakheji ye-PL/SQL eyakhelwe ngaphakathi ehlinzeka ngamathuluzi amaningi awusizo kubathuthukisi. Noma kunjalo, i-Oracle SQL iyaqhubeka nokuvela, ihlanganisa ukuguquguquka nokuqina, iqinisekisa ukuthi ihlala ibalulekile emkhakheni wokugcinwa kwedatha.
Imisebenzi Ehlobene Nokucindezela Kokwehlisa
Ngaphandle kwe-DROP CONSTRAINT, i-Oracle SQL inezitatimende zomyalo ezifana ENGEZA ISIVIVINYO, VUMELA UKUMVIMBELA, KHUBAZA ISIVIVINYO, VALIDATE CONSTRAINT, kanye NOVALIDATE CONSTRAINT. Le miyalo ibhekisela ekusebenzeni okuhlukile okunikeza ukulawula okuthuthukisiwe phezu kwezingqinamba zesizindalwazi.
Isibonelo, i-ADD CONSTRAINT ikuvumela ukuthi ungeze umkhawulo omusha etafuleni lakho, kuyilapho i-DISABLE CONSTRAINT ikuvumela ukuthi ukhubaze umkhawulo okwesikhashana. Ngakho-ke, ukuqonda le misebenzi kukuhlomisa ngomyalo ogcwele wesakhiwo sakho sesizindalwazi.
Amakhono abanzi e-Oracle SQL kanye nesethi yomyalo enamandla iyenza ibe ithuluzi elibalulekile ekuphathweni kwedathabhesi. Njengonjiniyela, kubalulekile ukuqonda lawa mathuluzi ukuze kube nesakhiwo sesizindalwazi esisebenza kahle nesiqinile.
