I-Art of Database Management: Uhlolojikelele lwamathebula e-Server Drop Temp Tables
Emkhakheni omkhulu wohlelo lwe-SQL, ukuphathwa nokuphathwa kwamatafula esikhashana kuyisihloko esibalulekile. Ithebula lethempeli elithobekile linendima ebalulekile okufanele liyidlale ekucutshungulweni nasekugcinweni kwedatha yesikhashana; ukubaluleka kwawo angeke kweqiswe. Kodwa-ke, imvelo yayo yesikhashana ingaphinda idale izithiyo uma kuziwa ekuphathweni kwedatha esebenza ngempumelelo. Enye inselele enjalo iphakama uma kunesidingo sokuhlola ukuthi ithebula lesikhathi likhona yini ngaphambi kokusebenzisa iskripthi, bese emva kwalokho, siliyeke uma likhona.
Amathebula okushisa e-server drop , uma ekhona, ayindlela thina bahleli bezinhlelo esiyisebenzisayo njengendlela engcono kakhulu yokuqinisekisa ukusebenza kwe-SQL okubushelelezi ngaphandle kokuphazanyiswa.
Isixazululo Sokuhlola Nokwehlisa Ithebula Lesikhashana
Njengazo zonke izinto ezinhle, i-SQL inendlela ejwayelekile yokuhlola ukuthi ithebula lesikhashana likhona yini ohlelweni lwedathabheyisi, futhi... yebo, ukuqagele kahle... I-SQL nayo inomyalo omuhle kakhulu wokuyilahla, uma ikhona. Nasi:
IF OBJECT_ID('tempdb..#TempTable') IS NOT NULL
DROP TABLE #TempTable
Lesi script se-SQL sihlola ukuthi ithebula lakho lesikhashana elithi #TempTable likhona noma alikho. Uma kwenzeka, iseva iwisa ithebula elishiwo.
Incazelo Yesinyathelo Nesinyathelo Yekhodi
Ake sihlukanise ikhodi futhi siqonde ingxenye ngayinye:
- IF OBJECT_ID('tempdb..#TempTable'): Lo myalo usetshenziselwa ukuhlola ukuthi into ethile, kulokhu, #TempTable yethu, ikhona kusizindalwazi se-temdb.
- AKUKHO NULL: Lesi sitatimende ngenxa yalokho sigcizelela umbandela we-IF, sithi uma i-OBJECT_ID ye-#TempTable ingeyize, okusho ukuthi ikhona, qhubekela esenzweni esilandelayo.
- DROP TABLE #TempTable: Uma izimo zangaphambili ziba yiqiniso, lo myalo uyala isistimu ukuthi yehlise, noma isuse i-#TempTable ohlelweni.
Imiqondo Ehlobene
Ngokunwetshwa, le ndlela yokuphatha ithebula ingasebenza futhi kumathebula angunaphakade. Ungashintsha i-tempdb kumyalo we-OBJECT_ID ngegama lesizindalwazi lapho itafula lakho olifunayo lihlala khona.
IF OBJECT_ID('DatabaseName..TableName') IS NOT NULL
DROP TABLE TableName
Ukuqonda ukusetshenziswa kwalesi simiso esilula kodwa esisebenza kahle sokuhlola nokulahla kungalula kakhulu ukusebenza kwesizindalwazi sakho, kwenze ikhodi yakho isebenze ngokushelela nangokufaneleka kakhulu.
Amalabhulali noma Imisebenzi Yemisebenzi Efanayo
I-SQL iphinde isinike imisebenzi enamandla ukuze siqhubekisele phambili imininingwane yethu egciniwe. Eminye imiqondo ehlobene nemisebenzi ithi TRUNCATE TABLE kanye ne-DROP DATABASE, esusa yonke imigqa etafuleni futhi isuse yonke isizindalwazi, ngokulandelana.
Ukubaluleka kokusebenzisa imikhuba emihle yokuphatha ithebula kanye nedathabheyisi akunakuphikiswa. Le mikhuba ibeka isisekelo sokusebenza kahle kwedathabheyisi ye-SQL kanye nokuphathwa kwedatha okuphumelelayo.
