Consider the following relation: r (A1, A2, A3). For all the states of the relation, the result of Query #1 is always the same as that of Query #2. Specify the primary key of the relation r (30 points); Explain why it must be the primary key. Query #1: sr1.A2=r2.A2 Ù r1.A1=r2.A1 (rr1 (r) ´ rr2 (r)) Query #2: select * from r as r1, r as r2 where r1.A1=r2.A1

Consider the following relation: r (A1, A2, A3). For all the states of the relation, the result of Query #1 is always the same as that of Query #2. Specify the primary key of the relation r (30 points); Explain why it must be the primary key. Query #1: sr1.A2=r2.A2 Ù r1.A1=r2.A1 (rr1 (r) ´ rr2 (r)) Query #2: select * from r as r1, r as r2 where r1.A1=r2.A1

Database Systems: Design, Implementation, & Management

12th Edition

ISBN:9781305627482

Author:Carlos Coronel, Steven Morris

Publisher:Carlos Coronel, Steven Morris

Chapter8: Advanced Sql

Section: Chapter Questions

Problem 18RQ

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Could you tell a step by step procedure of finding a super key for A relation R(A,B,C,D, E) having FD's AB → D, AC → E, BC → D, D → A, and E → B?
You are given a relation R with the following attributes R(A,B,C,D,E). Assume that you were given the following functional dependencies: • FD1= AB -> E • FD2: = D -> C (a) What is a valid key for this relation? justify your response. (b) Is this relation in 3NF (Third Normal Form)? Justify your response. If it is not in 3NF, normalize the relation and demonstrate all steps of normalization.
Consider a relation r(A, B, C), with an index on attribute A. Give an example of a query that can be answered by using the index only, without looking at the tuples in the relation. (Query plans that use only the index, without accessing the actual relation, are called index-only plans.)
question one: defined the following relation on A={0,2,5,6} Answer each of the following questions by listing the index of the relation. For example, for Part 1), if R1 and R2 and are reflexive, simply enter 1, 2 as the answer.1) Which relations are reflexive? 2) R0={(0,6),(6,6),(6,2),(0,0),(0,2),(2,2),(5,5)} 3) R1={(6,6),(2,2),(5,5),(0,0),(0,6)} 4) R2={(0,6),(6,6),(0,0),(5,6),(6,5),(5,0),(5,5),(2,2),(0,5) 5) R3={(5,5),(0,0),(6,6),(2,2) 6) R4={(5,5),(6,2),(6,6),(0,0),(6,5),(2,6),(2,2)} 1) Which relations are reflexive? 2) Which relations are symmetric? 3) Which relations are anti-symmetric? 4) Which relations are transitive? 5) Which relations are equivalence relations? 6) Which relations are partial orders? question two :defined the following relation on A={0,1,5,6} Answer each of the following questions by listing the index of the relation. For example, for Part 1), if R1 and R2 and are reflexive, simply enter 1, 2 as the answer. R0={(5,5),(0,0),(6,6),(1,1)}…
Give two examples of a relation and their candidate key
Consider the relation r(A, B, C) with the attribute A as the index. Give an example of a query that can be answered only by looking at the index, rather than the tuples in the relationship. (Index-only plans are query plans that just utilise the index and do not access the actual relation.)
Consider the relation r(A, B, C), where the index is the attribute A. Give an example of a query that can only be answered by looking at the index rather than the relationship's tuples. (Index-only plans are query plans that rely just on the index rather than the actual relation.)
Consider the following parameters of a relation r (A, B, C) in which A be the primary key. nr = 20000 V (B, r) = 120 max (C, r) = 500 min (C, r) = 0 Estimate the size of the following selection operations. a)σ A = k (r) b)σ A = k1 ∨ B = k2 (r) c)σ C >= Z ∧ C <= 105 (r)
Question 6. Consider the following relation: Invoice(Order_ID, Order_Date, Customer_ID, Customer_Name,Customer_Address,Product_ID, Product_Desc, Price, Order_Quantity) FD1 - Order_ID -> Order_Date, Customer_ID, Customer_Name, Customer_Address FD2 - Customer_ID -> Customer_Name, Customer_Address FD3 - Product_ID -> Product_Description, Price FD4 - Order_ID, Product_ID -> Order_Quantity What are the candidate keys of this relation? Give reasons to explain if this is in 1NF or not. If not, decompose it to 1NF. Give reasons to explain if this is in 2NF or not. If not, decompose it to 2NF. Give reasons to explain if this is in 3NF or not. If not, decompose it to 3NF.
I need help !!!! * Relations* 1. Given each relation write down the properties that the relation has. If the relation does not have a particular property, give an example showing why. a) R = \{(a,a), (a,c), (b,b), (c,b), (c,c)\}R={(a,a),(a,c),(b,b),(c,b),(c,c)} 2.The relation on any collection of sets where XX is related to YY if |X|=|Y|∣X∣=∣Y∣
Describe three scenarios when a surrogate key should replace a relation's primary key.
If there are more than one possible candidate keys, provide some instances of relations that have more than one.

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