Define the five basic relational algebra operations. Define the Join, Intersection, and Division operations in terms of these five basic operations.
? Selection and Projection (Unary)
? Cartesian Product, Union, and Set Difference (Binary).
? Can rewrite ?-Join in terms of the basic selection and Cartesian product operations:
? Can express the intersection operation in terms of the set difference operation:
? Can express the division operation in terms of the basic operations:
R 3 F S = ?F (R ? S)
R ? S = R - (R - S)
T 1 = ? C (R)
T 2 = ? C ( (S x T 1 ) - R)
T = T 1 - T 2
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What will be an ideal response?
Explain the difference between virtual functions, late binding, and polymorphism.
What will be an ideal response?
An object that absorbs red light and reflects or transmits blue light and green light would appear as what color?
A. cyan B. magenta C. yellow D. black
Consider the recovery aspects of the nested transactions. Assume that a withdraw transaction will abort if the account will be overdrawn and that in this case the parent transaction will also abort. Describe serially equivalent interleavings of T1, T2, U1 and U2 with the following properties:
(i) that is strict; (ii) that is not strict. To what extent does the criterion of strictness reduce the potential concurrency gain of nested transactions?