<p>给定关系R (A. B. C. D)与S (C. D. E.P).则<img alt="" src="htt
给定关系R
(A.
B.
C.
D)与S
(C.
D.
E.P).则
操作结果的属性个数分别为():与表达式
等价的SQL语句如SELECTR.B,R.C,R.DFROMR,SWHERE(请作答此空)
A.R.C=S.C OR R.D=S.D OR R.B
B.R.C=S.C 0R R.D=S.D OR R.B
C.R.C-S.C AND R.D-S.D AND R.B
D.R.C=S.C AND R.D-S.D AND R.B
正确答案是D