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Suppose relation R(A, B, C) has the following tuples: and relation S(A, B, C) has the...
Suppose: Relation S(B,C,D) has the following tuples: 68 79 Which of the following tuples is NOT in the result of the following query: SELECT Sum( BC) ASSUM, Max(D) AS MAX FROM S GROUP BY B; O (2,8,6) O (4,52,9) O (4,24,8) None of the above
1) Consider a relation R(A,B) with r tuples, all unique within R, and a relation S(B,C) with s tuples, all unique within S. Let t represent the number of tuples in R natural-join S. What is the value range of t? What is the value of t for R natural-join R (assuming no null values in R)? Explain your answer.
Suppose that we pick the following four tuples from a legal relation S (S has 100 tuples in total). S has the following schema: (A: integer, B: integer, C: integer) The four tuples are: (1,2,3), (4,2,3), (5,3,3) and (5,3,4). Which of the following functional (→)can you infer does not hold over relation S? a. A → B b. BC → A c. A → C d. AC → B
Consider the following tables R1 and R2: R1.A1 R1.B1 ------------ 1 1 NULL 2 3 NULL R2.A2 R2.B2 ------------ 1 1 NULL 2 3 NULL The tuple (3, NULL, 3, NULL) appears in the answer of which of the following SQL Statements? Check all that apply A. select * from R1,R2; B. select * from R1,R2 where R1.A1=R2.A2; C. select * from R1,R2 where R1.A1=R2.A2 and R1.B1=R2.B2; Suppose relation R(A,B,C) has the following tuples A B C ----- 2 3 4 5 3 4...
B. Consider the following two relations: Relation r Relations R Р 10 В a b 5 8. B b c A 10 25 10 C 6 3 5 15 25 a 6 show the results of the following relational algebraic operations. Give 0 as your answer if you think the operation makes no sense. However, if you believe an operation makes sense but no tuples should be returned, you should still draw the schema of the resulting table. n. r^r.p=s.A...
Question 1 (5 marks) Consider two relations called Item and Orderltem. Imagine that relation Item has 160,000 tuples and Orderltem has 200,000 tuples. Both relations store 100 tuples per a page. Consider the following SQL statement SELECT * FROM Item INNER JOIN OrderItem ON Item.ItemID-OrderItem. ItemID; We wish to evaluate an equijoin between Orderltem and Item, with an equality condition Item.ltemID Orderltem.ItemID. There are 802 buffer pages available in memory for this operation. Both relations are stored as (unsorted) heap...
Here is an instance of a relation R(A,B,C,D): Please just explain the feedback so I can attempt to solve it on my own! A B C D 1 2 3 4 1 3 3 3 1 3 3 4 1 2 3 3 2 2 4 4 2 4 2 4 2 4 4 4 2 2 2 4 Which of the following multivalued dependencies does this instance of R satisfy? A->> B BD ->> C D ->> AB B->>...
Suppose C = {a,b,c, d, e} and suppose we have a relation y which is transi- tive, and reflexive, we have ayb, byc, ayd, aye, cya. 1. Find all arrows which are a consequence of the given relations, and the relation properties. 2. Draw a diagram of your 7. , and 3. Compute the subrelation , consisting of all reversible arrows in find the equivalence classes. [There are three] 4. Draw the relation on the equivalence classes. 5. If this...
Database Structures
Question (50 points) . (10 points) Consider the join RDRa-Sb S, given the following information about the relations to be joined. Compute O costs for the following join operations. Relation R contains 4,000 tuples with blocking factor 40 .Relation S contains 2,000 tuples with blocking factor 40 Attribute a of relation R refers to attribute b of relation S Attribute b of relation S is the primary key for S Both relations are stored as simple heap files...
2. Let S 11,2,3,4,5, 6, 7,8,91 and let T 12,4,6,8. Let R be the relation on P (S) detined by for all X, Y E P (s), (X, Y) E R if and only if IX-T] = IY-T]. (a) Prove that R is an equivalence relation. (b) How many equivalence classes are there? Explain. (c) How mauy elements of [ø], the equivalence class of ø, are there? Explain (d) How many elements of [f1,2,3, 4)], the equivalence class of (1,2,3,...