DBI202Xuất hiện trong 1 đề thi
The table Arc(x,y) currently has the following tuples (note that there are duplicates): (1,2), (1,2), (2,3), (3,4), (3,4), (4,1), (4,1), (4,1), (4,2). Compute the result of the query: ```sql SELECT a1.x, a2.y, COUNT(*) FROM Arc a1, Arc a2 WHERE a1.y = a2.x GROUP BY a1.x, a2.y; ``` Which of the following tuples is in the result?
Các lựa chọn
A(3,1,6)
B(1,3,4)
C(2,4,6)
D(3,2,6)
E(3,1,2)