a) A=C(R(A,B,C)) b) <A,B>(R(A,B,C)) c) R(A,B,C)*S(C,D,E) f) R(A,B,C)-S(A,B,C) g)

Question

a) A=C(R(A,B,C))

b) <A,B>(R(A,B,C))

c) R(A,B,C)*S(C,D,E)

f) R(A,B,C)-S(A,B,C)

g) R(A,B,C)xS(A,B,C)

Explanation / Answer

a) sA=C(R(A,B,C)) - > (A, C) selects rows of A and C where the values of A and C are equal b) p(R(A,B,C)) - > (A, C) erases column B and the result A and C by eliminating duplicates c) R(A,B,C)*S(C,D,E) - > (A, B, C, D, E) gives the product of all the values A, B, C,D and E d) R(A,B,C) S(A,B,C) - > (A, B, C) all the values in both the schemas with no duplicates – A, B, C e) R(A,B,C) S(A,B,C) - > (A, B, C) values that are in common in both the schemas – A, B, C f) R(A,B,C)-S(A,B,C) - > (A, B, C) eliminates all the values from R that are in S and gives the values of R g) R(A,B,C)xS(A,B,C) - > (A, B, C) product of all the values in both the schemas without duplicates h) R(A,B) S(A) - > (B) the values of R by eliminating the columns contained in S

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