| 71. | Consider the following ORACLE relations:
One (x, y) = {<2, 5>, <1, 6>, <1, 6>, <1, 6>, <4, 8>, <4, 8>} Two (x, y) = {<2, 55>, <1, 1>, <4, 4>, <1, 6>, <4, 8>, <4, 8>, <9, 9>, <1, 6>} Consider the following two SQL queries SQ1 and SQ2: SQ1 : SELECT * FROM One) EXCEPT (SELECT * FROM Two); SQ2 : SELECT * FROM One) EXCEPT ALL (SELECT * FROM Two); For each of the SQL queries, what is the cardinality (number of rows) of the result obtained when applied to the instances above? |
| a. | 2 and 1 respectively |
| b. | 1 and 2 respectively |
| c. | 2 and 2 respectively |
| d. | 1 and 1 respectively |
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Answer: (b).1 and 2 respectively
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| 72. | Which one of the following pairs is correctly matched in the context of database design?
List – I List – II (Database term) (Definition) I. Specialization A. Result of taking the union of two or more disjoint (lower-level) entity sets to produce a higher-level entity set. II. Generalization B. Express the number of entities to which another entity can be associated via a relationship set. III. Aggregation C. Result of taking a subset of a higher-level entity set to form a lower-level entity set. IV. Mapping cardinalities D. An abstraction in which relationship sets (along with their associated entity sets) are treated as higher-level entity sets, and can participate in relationships. Codes : I II III IV |
| a. | D A B C |
| b. | D C B A |
| c. | C D A B |
| d. | C A D B |
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Answer: (d).C A D B
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| 73. | Consider a hash table of size m = 10000, and the hash function h(K)=floor(m(KAmod1)) for A = (√5 – 1)/2. The key 123456 is mapped to location ............... |
| a. | 46 |
| b. | 41 |
| c. | 43 |
| d. | 48 |
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Answer: (b).41
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| 74. | Which of the following statements concerning Object-Oriented databases is FALSE? |
| a. | Objects in an object-oriented database contain not only data but also methods for processing the data. |
| b. | Object-oriented databases store computational instructions in the same place as the data. |
| c. | Object-oriented databases are more adapt at handling structures (analytical) data than relational databases. |
| d. | Object-oriented databases store more types of data than relational databases and access that data faster. |
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Answer: (c).Object-oriented databases are more adapt at handling structures (analytical) data than relational databases.
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| 75. | In distributed databases, location transparency allows for database users, programmers and administrators to treat the data as if it is at one location. A SQL query with location transparency needs to specify: |
| a. | Inheritances |
| b. | Fragments |
| c. | Locations |
| d. | Local formats |
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Answer: (b).Fragments
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| 76. | Consider the relations R(A,B) and S(B,C) and the following four relational algebra queries over R and S:
I. πA,B(R⋈S) II. R⋈πB(S) III. R∩(πA(R) Χ πB(S)) IV. πA,R.B(R Χ S) where R.B refers to the column B in table R. One can determine that: |
| a. | I, III and IV are the same query. |
| b. | II, III and IV are the same query. |
| c. | I, II and IV are the same query. |
| d. | I, III and III are the same query. |
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Answer: (d).I, III and III are the same query.
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| 77. | Which of the following statements is TRUE?
D1: The decomposition of the schema R(A,B,C) into R1(A,B) and R2(A,C) is always lossless. D2: The decomposition of the schema R(A,B,C,D,E) having AD→B, C→DE, B→AE, AE→C into R1(A,B,D) and R2(A,C,D,E) is lossless. |
| a. | Both D1 and D2 |
| b. | Neither D1 and D2 |
| c. | Only D1 |
| d. | Only D2 |
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Answer: (d).Only D2
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| 78. | Consider the following ORACLE relations:
R(A,B,C) = {<1,2,3>, <1,2,0>, <1,3,1>, <6,2,3>, <1,4,2>, <3,1,4>} S(B,C,D) = {<2,3,7>, <1,4,5>, <1,2,3>, <2,3,4>, <3,1,4>} Consider the following two SQL queries SQ1 and SQ2: SQ1: SELECT R.B, AVG(S.B) FROM R, S WHERE R.A = S.C AND S.D < 7 GROUP BY R.B; SQ2: SELECT DISTINCT S.B, MIN (S.C) FROM S GROUP BY S.B HAVING COUNT (DISTINCT S.D) > 1; If M is the number of tuples returned by SQ1 and N is the number of tuples returned by SQ2 then |
| a. | M=4, N=2 |
| b. | M=5, N=3 |
| c. | M=2, N=2 |
| d. | M=3, N=3 |
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Answer: (a).M=4, N=2
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| 79. | Semi-join strategies are techniques for query processing in distributed database system. Which of the following is a semi-join technique? |
| a. | Only the joining attributes are sent from one site to another and then all of the rows are returned. |
| b. | All of the attributes are sent from one site to another and then only the required rows are returned. |
| c. | Only the joining attributes are sent from one site to another and then only the required rows are returned. |
| d. | All of the attributes are sent from one site to another and then only the required rows are returned. |
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Answer: (c).Only the joining attributes are sent from one site to another and then only the required rows are returned.
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| 80. | Consider a “CUSTOMERS” database table having a column “CITY” filled with all the names of Indian cities (in capital letters). The SQL statement that finds all cities that have “GAR” somewhere in its name, is: |
| a. | Select *from customers where city=’%GAR%’; |
| b. | Select *from customers where city=’$GAR$’; |
| c. | Select *from customers where city like ‘%GAR%’; |
| d. | Select *from customers where city as ’%GAR’; |
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Answer: (c).Select *from customers where city like ‘%GAR%’;
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