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)寫數(shù)據(jù)在事務(wù)開始時(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；寫數(shù)據(jù)時(shí)加X(jué)鎖，寫完即釋放X鎖
C.讀數(shù)據(jù)時(shí)加S鎖，讀完即釋放S鎖；對(duì)寫數(shù)據(jù)是在事務(wù)開始時(shí)加X(jué)鎖，事務(wù)完成后釋放X鎖
D.在事務(wù)開始時(shí)即對(duì)要讀、寫的數(shù)據(jù)加鎖，等事務(wù)結(jié)束后再釋放全部鎖