DBI202 SET 2

a

QN=1 (6797) A ____ is a powerful tool for creating and managing large amounts of data efficiently and allowing it to persist over long periods of time, safely a. DBMS b. Database c. Excel d. None of the others

b

QN=10 (6830) Which one of the following is NOT a DML command? a. DELETE b. ALTER TABLE c. INSERT d. UPDATE

a

QN=12 (7962) What is a functional dependency? a. A functional dependency (A->B) occurs when the attribute A uniquely determines B b. A functional dependency (A->B) occurs when the attribute B uniquely determines A

a

QN=14 (7970) What is a key attribute in a relation? a. A key attribute is an attribute that belongs to one of the keys of the relation b. A key attribute is an attribute that belongs to one of the super keys of the relation

a

QN=15 (7984) Which of the following relations is in Boyce-Codd Normal Form (BCNF)? a. R(ABCD) with FD's: BD -> C ; AB -> D ; AC -> B ; BD -> A b. R(ABCD) with FD's: BC -> A ; AD -> C ; CD -> B ; BD -> C c. R(ABCD) with FD's: A -> C ; B -> A ; A -> D ; AD -> C d. R(ABCD) with FD's: A -> D ; C -> A ; D -> B ; AC -> B

e

QN=16 (7991) 3NFconcept is related to (choose 1 answer only): a. Atomic definition b. Full dependency definition c. Transitive dependency definition d. Super Key definition e. All of the others

a

QN=17 (7979) The relation R(ABCD) has following FDs: {ACD -> B ; AC -> D ; D -> C ; AC -> B} Choose the correct statement about R: a. R is in 3NF b. R is in 2NF only, not higher c. R is in 1NF only, not higher d. None of the others

c

QN=18 (7975) Let R(A,B,C,D) with the following FDs: {AB->C, AC->B, AD->C} Choose a correct statement about R: a. R is in BCNF b. R is in 3NF c. R is in 2NF d. None of the others

b

QN=19 (8002) Which of the following statements is correct? a. All relations in 3NF are also in BCNF b. For any relation schema, there is a dependency-preserving decomposition into 3NF c. All relations in 2NF are also in BCNF

d

QN=20 (8005) Which of the following statements is true? a. BCNF condition guarantees the non existence of the anomalies. b. In BCNF condition, the left side of every non trivial FD must be a super key. c. Any two-attribute relation is in BCNF. d. All of the others.

a

QN=21 (7995) How to eliminate anomalies when we design a database? a. We should decompose relation to eliminate anomalies b. We should join relations to eliminate anomalies c. We should union relations to eliminate anomalies d. None of the others

a

QN=22 (7994) What is the goal of decomposition when designing a database? a. The goal of decomposition is to replace a relation by several relations that do not exhibit anomalies b. The goal of decomposition is to increase the speed of the database c. The goal of decomposition is to increase the security of the database d. None of the others

d

QN=24 (8029) Consider the following statement: "Entity Sets and their attributes should reflect the reality" That above statement describes which principle? a. Avoid Redundancy Principle b. Simplicity Count Principle c. Limit the use of weak entity sets principle d. Faithfulness principle

a

QN=25 (8010) Look at the following statements: (a)We should pick the right kind of elements (b) When an entity has no non-primary key attribute, we should convert that entity to an attribute (c) Use weak entities when-ever possible (d) Always make redundancies a. (a) and (b) are correct b. (a) and (c) are correct c. (a) and (d) are correct d. (b) and (c) are correct

b

QN=26 (8017) The ER Diagram uses three principle element types: a. Entity sets, Attributes and Constraints b. Entity sets, Attributes, and Relationships c. Attributes, Constraints, and Relationships d. Entity sets, Constraints, and Relationships

c

QN=27 (8030) The binary relationship between classes in UML is called ... a. Aggregation b. Composition c. Association d. Relation

a

QN=28 (8231) Consider the Datalog rule H(x,y) <- S(x, y) AND x > 2 AND y < 6. Relation S(x, y) has 3 tuples (2, 3), (3, 5), and (4, 6). What is about H? a. H has a tuple (3, 5) b. H has a tuple (2, 3) c. H has 2 tuples (2, 3) and (3, 5) d. H has 3 tuples (2, 3) and (3, 5) and (4, 6)

a

QN=3 (6800) What is the hierarchical data model? a. A hierarchical data model is a data model in which the data is organized into a tree-like structure b. A hierarchical data model is a data model in which the data is organized into a table-like structure c. A hierarchical data model is a data model in which the data is organized into a graph-like structure d. None of the others

a

QN=30 (8232) Suppose that tuple t appears, respectively, x, y, and z times in the relations X, Y, and Z. Let t appear w times in the relation: X union (Y intersect Z). Which of the following inequalities is true ? a. w <= x+y b. w <= y+z c. w >= z d. w <= max(x,y)

a

QN=33 (8522) The table Arc(x,y) currently has the following tuples (note there are duplicates): (See picture) Compute the result of the query: SELECT x, COUNT(y) FROM Arc GROUP BY x; Which of the following tuples is in the result? [file:8522.jpg] a. (4,4) b. (4,5) c. (4,6) d. (4,7) e. (4,8)

d

QN=34 (8501) Suppose the relation S(B,C,D) has tuples: B C D ------------------------------------ a 4 6 c 6 8 c 5 5 e 9 9 F 10 10 c 7 9 Which one of the followings will appear in the result of the following query: SELECT B, SUM(C) FROM S GROUP BY B a. (c,11) b. (c,13) c. (c,12) d. (c,18)

b

QN=35 (8503) Given the relation Employee(SSN, FNAME, LNAME, SALARY, DepartmentNo). Select the right query below to count the number of employees in each department. a. SELECT COUNT(*) FROM Employee b. SELECT DepartmentNo, COUNT(*) FROM Employee GROUP BY DepartmentNo c. SELECT DepartmentNo, COUNT(*) FROM Employee d. None of the others

d

QN=36 (8505) Suppose the relation S(B,C,D) has tuples: B C D ------------------------------------ a 4 6 c 6 8 c 5 5 e 9 9 f 10 10 c 7 9 What row that appears in the result of the following query: SELECT SUM(C), SUM(D) FROM S WHERE D < 9 AND D > 5 a. (10,11) b. (10,12) c. (10,13) d. (10,14)

a,b

QN=38 (8532) Here are two relations, R(A,B), S(C,D). Their current values are: R A B ------------------- 1 4 2 5 8 6 4 7 S C D ------------------- 0 1 1 0 2 1 5 8 Compute the result of the query: SELECT A, B, C, D FROM R RIGHT OUTER JOIN S ON R.A = S.C Identify, in the list below, 2 rows that appears in the result. a. (null, null, 0, 1) b. (null, null, 5, 8) c. (8, 6, null, null) d. (4, 7, null, null)

a

QN=39 (8531) Here are three relations, R(A,B), S(C,D). Their current values are: R A B ------------------- 1 4 2 5 3 6 4 7 S C D ------------------- 0 1 1 0 2 1 Compute the result of the query: SELECT A, B, C, D FROM R LEFT OUTER JOIN S ON R.A = S.C Identify, in the list below, the row that appears in the result. a. (4, 7, null, null) b. (4, 7, 0, 1) c. (4, 7, 1, 0) d. (4, 7, 2, 1)

a

QN=4 (6795) In _____ Data Model, the data and relations between them are organized in tables a. Relational b. Network c. Flat-file d. Object-oriented e. Tree-based

a

QN=40 (8534) A tuple which fails to participate in a join is called: a. dangling tuple b. child tuple c. parent tuple d. neighbor tuple

a

QN=41 (8538) (TRUE OR NULL) return: a. TRUE b. FALSE c. NULL d. None of the others

b

QN=42 (8552) Choose one correct statement: a. Two null values are equal b. Comparisons between two null values, or between a NULL and any other value, return unknown c. Comparisons between two null values, or between a NULL and any other value, return FALSE

a

QN=43 (8554) For what values of x, y, and z, including NULL, does the Boolean expression x <= 100 AND NOT(y >= 15 OR z = 35) have the truth value UNKNOWN? Identify one of those values from the list below. a. x = NULL, y = 0, z = 4. b. x = -2, y = -2, z = -2. c. x = 3, y = 0, z = 7. d. x = 2, y = -1, z = 6.

a

QN=53 (9176) The SQL operations that are performed while a connection is active form a ____ a. Session b. Catalog c. Module d. None of the others

a

QN=44 (8551) Choose one correct statement: a. No two null values are equal b. Two null values are equal c. Comparisons between two null values, or between a NULL and any other value, return FALSE

d

QN=46 (8559) A database transaction, by definition, must be ACID (atomic, consistent, isolated and durable). What does "Isolated" mean? a. "Isolated" means that: Transactions provide an "all-or-nothing" proposition, stating that each work-unit performed in a database must either complete in its entirety or have no effect whatsoever b. "Isolated" means that: Transactions must not violate any integrity constraints during its execution c. "Isolated" means that: Transactions that have committed will survive permanently d. "Isolated" means that: how/when the changes made by one operation in one transaction become visible to other concurrent operations in other transactions

a

QN=47 (8578) What one is a wildcard used for pattern matching? a. "%" (for multi-character substitution) b. "?" (for single character substitution) c. "?" (for multi-character substitution)

b

QN=48 (8573) Suppose we have a relation instance R(A,B,C) as following: R A B C ---------------------------------- 1 2 3 4 5 6 7 8 9 Which is the result of the query: SELECT SUM(B) FROM R WHERE C > 10 a. 0 b. NULL c. 3 d. 10

e

QN=49 (8589) Choose the most correct statement about PRIMARY KEY: a. The PRIMARY KEY constraint uniquely identifies each record in a database table b. Primary keys must contain unique values c. A primary key column cannot contain NULL values d. Each table should have a primary key, and each table can have only ONE primary key e. All of the others

a

QN=5 (6833) Why the intersection operator is not called a primitive relational algebra operator? a. Because the intersection operator can be expressed through the union operator and the difference operator b. Because the intersection operator can be expressed through the selection operator and the projection operator c. Because the intersection operator can be expressed through the product operator and the projection operator d. Because the intersection operator can be expressed through the selection operator and the product operator

a

QN=50 (8584) Foreign key constraints are created by using "_____" keyword to refer to the primary key of another table a. REFERENCES b. POINT TO c. REFER d. None of the others

b

QN=52 (8616) The most useful index on a relation is an index on its key. This is because: a. The index on non key attribute(s) runs slower b. The search operation based on the primary key is commonly used. c. The index on non key attribute(s) makes update operations to the relation more complex and time-consuming d. All of the others

a

QN=54 (9171) In PSM, the difference between a stored procedure and a function is that: a. A function has the return statement. b. We can declare local variables in a function. c. Loops are not allowed in a function. d. All of the others.

a

QN=55 (9182) The aim for the Object-relational database is to bridge the gap between conceptual data modelling techniques such as Entity-relationship diagram (ERD) and object-relational mapping (ORM), which often use classes and inheritance, and relational databases, which do not directly support them a. True b. False

d

QN=56 (9189) Choose the correct statement: a. A User-Defined Type (UDT) in SQL can be the type of a table b. A UDT can be the type of an attribute belonging to some table c. The form of UDT definition is: CREATE TYPE T AS (<primitive type | attribute declarations>) d. All of the others

a

QN=57 (9192) ______ is a set of markup declarations that define a document type for SGML-family markup languages (SGML, XML, HTML) a. Document Type Definition b. Document Definition Language c. Document Manipulation Language d. Document Control Language

b

QN=58 (9198) A ____ document defines the XML document structure with a list of legal elements and attributes a. XML b. DTD c. XSLT d. SGML

c

QN=6 (6814) In SQL , the command/statement that let you add an attribute to a relation schema is ....... a. Insert b. Update c. Alter d. None of the others

a

QN=60 (9207) A ____ is the framework under which data may exist and SQL operations on data may be executed a. SQL Environment b. SQL Statement c. SQL Parser d. SQL Optimizer

a

QN=7 (6826) To update a relation's schema, which one of the following statements can be used? a. ALTER TABLE b. SELECT c. INSERT d. UPDATE

a

QN=8 (6832) Schema-altering commands are known as _________ commands. a. Data Definition Language b. Data Manipulation Language c. Data Controlling Language d. None of the others