Database Lossless Join

Question

Answer 1

	A	B	C	D	E	G
R1	X	X
R2		X	X
R3	X	X		X	X
R4					X	X

Applying functional dependencies E-> G, we can put X in column G of R3, but we cannot get any row with all X.

So D1 is lossy.

	A	B	C	D	E	G
R1	X	X	X
R2	X		X	X	X
R3	X			X		X

Applying functional dependencies, AC-> B, we can put X in B. Still no row with all X.

So lossy.

Hence option D.