database Relation Algebra and sql

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fuva777

Computer Science

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must show all work and correct answers. please do not bid if you are not 100% sure about what you are doing.  i won't accept incomplete or wrong work. see attachment for questions.

work5.pdf


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Problem 1 a) Suppose there are two relations, R1 and R2. Relation R1(A,B) has the tuples: AB 0 1 2 3 4 5 and the relation R2(B,C,D) has tuples: BCD 1 3 5 3 5 7 3 6 8 Compute the natural join of R1 and R2. 1 b ) Suppose there are two relations, R1 and R2. Relation R1(A,B) has the tuples: AB 0 1 2 3 4 5 and the relation R2(B,C,D) has tuples: BCD 1 3 5 3 5 7 3 6 8 Compute the theta-join R1 ⋈R1.A < R2.C AND R1.B < R2.D R2. (must show the steps of your work) 2 c ) Suppose there are two relations, R1 and R2. Relation R1(A,B,C) has the tuples: ABC 2 3 4 5 3 4 5 6 7 3 6 4 2 3 7 and relation R2(A,B,C) has the tuples: ABC 3 6 4 3 6 5 5 6 7 2 3 4 Compute (R1 – R2)∪(R2 – R1), often called the "symmetric difference" of R1 and R2. (1) Show (R1 – R2) =? (2) Show (R2 – R1) =? (3) Show (R1- R2)∪(R2 – R1) =? 3 d ) Suppose there are two relations, R1 and R2. Relation R1(A,B,C) has the tuples: ABC 1 2 3 1 2 3 4 5 6 2 5 3 1 2 6 and relation R2(A,B,C) has the tuples: ABC 2 5 3 2 5 4 4 5 6 1 2 3 Compute the bag union, R1∪R2. e) Suppose relation S(A,B,C) has the tuples: ABC 0 1 2 0 1 3 4 5 6 4 6 3 Compute the generalized projection πB,A+C,B(S) 4 f ) Suppose relation S(A,B,C) has the tuples: ABC 1 2 3 1 2 3 2 3 1 3 1 2 2 2 3 2 3 3 Using bag projection and intersection, compute πA,B(S) ∩ ρR(A,B)(πB,C(S)). (must show the steps of your work ) g) Suppose relation S(A,B,C) has the tuples: ABC 1 2 3 1 2 3 2 3 1 3 1 2 2 2 3 2 3 3 Using bag projection and difference, compute πA,B(S) – ρR(A,B)(πB,C(S)). (must show the steps of your work) 5 h ) Suppose there are two relations, R1 and R2. Relation R1(A,B) has the tuples: AB 0 1 2 3 4 5 and the relation R2(B,C,D) has tuples: BCD 1 3 5 3 5 7 3 6 8 Compute the outerjoin of R1 and R2, where the condition is: R1.A>R2.B AND R1.B=R2.C. (Which tuples of R1 or R2 are dangling (and therefore needs to be padded in the outerjoin)?) Problem #2 (a). Query Statement: List the model for PCs that are faster than 2Ghz? Translate the Query Statement into Relational Algebra. (b). Using Relational Algebra to express the following SQL statements: SELECT empno FROM employee WHERE depno IN (select depno from employee where name = ‘Jim Smith‘) 6 Problem#3 Translate the following SQL statements into Relational Algebra Tree. SELECT FROM WHERE AND AND AND EName Job, Employee, Group Group.ENO=Employee.ENO Group.JNO=Job.JNO EName“C. Wu” Job.Name=“Database” AND DUR=12 ; 7
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