Video: Dab tsi yog kev siv rollback hauv SQL?
2024 Tus sau: Lynn Donovan | [email protected]. Kawg hloov kho: 2023-12-15 23:47
Hauv SQL ntawv , ROLLBACK yog ib qho lus txib uas ua rau tag nrho cov ntaub ntawv hloov pauv txij li qhov kawg BEGIN UA HAUJ LWM, lossis PIB TRANSACTION kom muab pov tseg los ntawm kev sib raug zoo database tswj systems (RDBMS), kom lub xeev cov ntaub ntawv yog " dov rov qab "mus rau txoj kev uas nws tau ua ua ntej cov kev hloov pauv tau ua.
Hauv qhov no, dab tsi yog kev siv kev cog lus thiab rollback hauv SQL?
Lub ntsiab sib txawv ntawm cov COMMIT thiab ROLLBACK nqe lus ntawm SQL ntawv yog hais tias kev tua ntawm COMMIT nqe lus ua rau txhua qhov kev hloov kho los ntawm qhov tam sim no kev pauv nyiaj ua tas mus li. Ntawm qhov tod tes, kev tua ntawm ROLLBACK erases tag nrho cov kev hloov kho los ntawm tam sim no kev pauv nyiaj.
Kuj Paub, thaum rollback ntawm kev lag luam tuaj yeem tshwm sim? A rov qab tsis xav tau tshwm sim raws li koj hais "thaum cog lus", uas kuv twv koj txhais tau tias "thaum sim ua txhaum." A kev lag luam tuaj yeem rov qab txhua lub sijhawm tom qab pib. Qee zaum, a rollback yuav tshwm sim txiav txim siab vim muaj kev cuam tshuam lossis kev txwv tsis pub ua txhaum cai.
Tsis tas li lo lus nug yog, dab tsi yog kev siv kev cog lus hauv SQL?
Cov COMMIT hais kom ua yog cov lus txib siv kom txuag tau cov kev hloov pauv uas tau thov los ntawm kev hloov pauv mus rau lub database. Cov COMMIT hais kom txuag tag nrho cov kev pauv mus rau lub database txij li thaum kawg COMMIT los yog ROLLBACK hais kom ua.
Koj txhais li cas los ntawm rollback?
A rov qab yog kev ua haujlwm ntawm kev rov ua kom cov ntaub ntawv rov qab mus rau lub xeev dhau los los ntawm kev tshem tawm cov kev hloov pauv tshwj xeeb lossis kev hloov pauv. Rollbacks yog ua tiav los ntawm database systems lossis manually los ntawm cov neeg siv.
Pom zoo:
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