<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(请作答此空):与表达式
等价的SQL语句如SELECTR.B,R.C,R.DFROMR,SWHERE()
A.8,6
B.6，6
C.8，8
D.7，6
正确答案是A
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(请作答此空):与表达式等价的SQL语句如SELECTR.B,R.C,R.DFROMR,SWHERE()
A.8,6
B.6，6
C.8，8
D.7，6
正确答案是A