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If R1 and R2 are two relations or functions, then the result of R3 = R1 × R2 is the combination of tuples that are in R1 and R2. The product is associative and commutative.
Degree (R3) =Degree of (R1) + Degree (R2).
In case, R3 will have tuples such that R3 = {t1 || t2 | R1 ∋ t1 ∧ R2 ∋ t2}.
Example:
R2
A
B
A1
B1
A2
B2
A3
B3
A4
B4
R1
C
C1
C2
R3 = R1 × R2 is
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What is a PROJECT operation? The project operation is a unary operation that returns its argument relation with particular attributes left out. Projection is shown by pie (π).
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Suppose R is a relation with attributes A1, A2,..., An. As a function of n, tell how many superkeys R has, if: 1.1 The only key is A1. 1.2 The only key is A1 and A2. 1.3 The o
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