A.丟失修改 B.讀臟數(shù)據(jù) C.不可重復(fù)讀 D.數(shù)據(jù)不一致
A.丟失修改 B.不可重復(fù)讀 C.讀臟數(shù)據(jù) D.死鎖
A.對(duì)讀數(shù)據(jù)不加鎖,對(duì)寫(xiě)數(shù)據(jù)在事務(wù)開(kāi)始時(shí)加X(jué)鎖,事務(wù)完成后釋放X鎖 B.讀數(shù)據(jù)時(shí)加S鎖,讀完即釋放S鎖;寫(xiě)數(shù)據(jù)時(shí)加X(jué)鎖,寫(xiě)完即釋放X鎖 C.讀數(shù)據(jù)時(shí)加S鎖,讀完即釋放S鎖;對(duì)寫(xiě)數(shù)據(jù)是在事務(wù)開(kāi)始時(shí)加X(jué)鎖,事務(wù)完成后釋放X鎖 D.在事務(wù)開(kāi)始時(shí)即對(duì)要讀、寫(xiě)的數(shù)據(jù)加鎖,等事務(wù)結(jié)束后再釋放全部鎖