DBI

a

QN=15 (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=1 (6808) What is a database? a. A database is a collection of information that is organized so that it can easily be accessed, managed, and updated b. A database is a collection of data files c. A database is a collection of records d. A database is a collection of tuples

b

QN=10 (6811) The relational operator that adds all possible pairs of rows from two tables is known as the .... operator. a. union b. product c. join d. selection

a

QN=11 (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=12 (6813) Which statement is used to remove a column named D from the relation R? a. ALTER TABLE R DROP COLUMN D; b. ALTER TABLE R DROP COLUMN D [DataType]; c. ALTER TABLE R DELETE COLUMN D; d. ALTER TABLE R DELETE COLUMN D [DataType];

a

QN=13 (7956) Let R(ABCDEFGH) satisfies the following functional dependencies: A -> B, CH -> A, B -> E, BD -> C, EG -> H, DE -> F. Which of the following FDs is also guaranteed to be satisfied by R? a. ADG -> CH b. ACG -> DH c. CGH -> BF d. BCD -> FH

a

QN=14 (7959) Give a relation R(A,B,C,D) like this: A B C D --------------------------------------------------- 1 2 3 6 1 3 3 6 2 4 5 7 Please choose the in-correct functional dependency: a. A -> B b. A ->C c. A->D d. C->D

a

QN=16 (7966) Suppose R is a relation with attributes A1, A2, A3, A4. The only key of R is {A1, A2}. So, how many super-keys do R have? a. 4 b. 8 c. 12 d. 16

a

QN=17 (7964) Consider a relation R(A,B,C,D,E) with functional dependencies AB->C, B->D, and C->E. What is the key for R (choose one) a. AB b. AC c. AD d. AE

a

QN=18 (7973) Suppose R is a relation with attributes A1, A2, A3, A4. The only key of R is A1. So, how many super-keys R has? a. 8 b. 9 c. 10 d. 11

b

QN=19 (7977) The relation R(ABCD) has following FDs: { AB -> C ; ABD -> C ; ABC -> D ; AC -> D} Choose a correct statement about R? a. R is in 3NF b. R is not in 3NF c. R is in BCNF

a

QN=2 (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

c

QN=20 (7978) The relation R(ABCD) has following FDs: { A -> B ; B -> A ; A -> D ; D -> B } a. R is in 3NF b. R is not in 3NF c. R is not in 2NF d. None of the others

a

QN=21 (7987) What is the condition that a relation schema R is in BCNF (Boyce-Codd Normal Form)? a. It is in 3NF and satisfies an additional constraint that for every non-trivial FD: X->A, X must be a candidate key b. If every non-prime attribute A in R is fully functionally dependent on primary key c. If every non prime attribute is not-transitively dependent on primary key d. None of the others

d

QN=22 (7989) The highest normal form for relation schema R(A,B,C) with functional dependencies: F = {AB-> C; B->A; C->B } is: a. 1NF b. 2NF c. 3NF d. BCNF

a

QN=23 (7974) Suppose we have a relation R(ABCD) with FD's: BD -> C ; AB -> D ; AC -> B ; BD -> A a. R is in BCNF b. R is not in BCNF c. R is not in 3NF d. R is not in 2NF

c

QN=24 (7992) Normalization is a process of analyzing the given relation schema based on their Functional Dependencies (FDs) and primary keys to achieve the following: a. Minimizing redundancy b. Minimizing insertion anomalies c. All of the others d. Minimizing deletion and update anomalies

a

QN=25 (8003) Look at the following statements: (a) For any relation schema, there is a dependency-preserving decomposition into 3NF (b) For any relation schema, there is not dependency-preserving decomposition into 3NF (c) For any relation schema, there is dependency-preserving decomposition into BCNF (d) For some relation schema, there is not dependency-preserving decomposition into BCNF a. (a) and (d) are true b. (a) and (b) are true c. (a) and (c) are true d. (b) and (d) are true

d

QN=26 (7998) Normalization is a. the process of ensuring that a relational database has at least two tables. b. the process of ensuring that each table has a key c. a process whereby a limit is put on the number of fields a record can contain d. a process whereby the design of a table (relation) is decomposed into more tables that more precisely fit the relational model

c

QN=27 (8032) An association class in UML is similar to ______ in the ER model a. attributes on a relationship b. Attributes c. Entities d. entity sets

a

QN=28 (8009) In UML, what is the difference between an aggregation and a composition? a. In composition, when the owning object is destroyed, so are the contained objects. In aggregation, this is not necessarily true. b. In aggregation, when the owning object is destroyed, so are the contained objects. In composition, this is not necessarily true. c. All of the others d. There is no difference between an aggregation and a composition

a

QN=29 (8021) What is an entity? a. an entity is an existing or real thing b. an entity is a data structure used to provide quick access to data in a database table or view c. an entity is a data structure that is used to uniquely defines the row in the table d. an entity is a specialized type of stored procedure that is bound to a table or view

a

QN=3 (6804) Most of the database systems in use today are based on the _____ data model a. Relational b. Network c. Flat-file d. Object-oriented e. Tree-based f. Object-relational

a

QN=30 (8016) What is an Entity Set? a. It is a collection (set) of entities that have same attributes b. It is a "thing" in the real world with an independent existence. c. It is a collection of entities of a particular entity type grouped together into an entity set. d. None of the others

a

QN=31 (8013) A(n) _____ provides a means to analyze business requirements so as to standardize organizational vocabulary, enforce business rules, and ensure adequate data quality a. Entity Relationship Diagram b. Relation Schema Design

a

QN=32 (8033) In UML, a _____ between classes is called an association a. binary relationship b. multi-way relationship c. none of the others

b

QN=33 (8012) Consider the following statement: "When drawing ERD, you should avoid introducing more elements into your design than necessary" 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=34 (8225) ___ operators are operators that operate on groups and return a number for each group a. Aggregation b. Grouping c. Duplicate-elimination d. Extended projection

a

QN=35 (8230) For what values of x, y, and z, including NULL, does the Boolean expression x <= 3 OR NOT(y >= 1 AND z = 5) have the truth value FALSE? Identify one of those values from the list below a. x = 4, y = 3, z = 5. b. x = 3, y = 1, z = 5. c. x = NULL, y = 2, z = 5. d. x = NULL, y = 3, z = 5.

?

QN=36 (8220) Suppose relation R(A,B,C) has the tuples: A B C ---------------------------------- a b c a b c d e f b e c a b f and relation S(A,B,C) has the tuples: A B C ----------------------------------- b e c b e d d e f A b c Compute the bag union R [union] S, and then indicate which of the following is true about this bag. a. (d,e,f) appears twice in the result. b. (a,b,c) appears twice in the result. c. (a,b,c) appears once in the result. d. (d,e,f) appears once in the result.

a

QN=37 (8223) See picture: a. S(t,y,l,g,s,p) <- Movies(t,y,l,g,s,p) AND length≥100 AND studioName='Fox' b. S(t,y,l,g,s,p) <- Movies(t,y,l,g,s,p) AND length ≥ 100 c. S(t,y,l,g,s,p) <- Movies(t,y,l,g,s,p) AND studioName = 'Fox' d. S(t,y,l,g,s,p) <- Movies(t,y,l,g,s,p) AND length > 100 AND studioName='Fox'

a

QN=38 (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=39 (8508) Suppose we have a relation instance R(A,B,C) as following: R A B C ---------------------------------- 1 NULL 3 4 NULL 6 7 8 9 Which is the result of the query: SELECT COUNT(B) FROM R a. 1 b. 3 c. 8 d. None of the others

a

QN=4 (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

c

QN=40 (8512) Suppose relation R(a,b,c) has the following tuples: A B C ----------------------------------- 1 1 3 1 2 3 2 1 4 2 3 5 2 4 1 3 2 4 3 3 6 Which tuple is contained in the result of the following query: SELECT a, COUNT(DISTINCT B) FROM R GROUP BY a HAVING SUM(B) >3; a. (2,10) b. (3,7) c. (2,3) d. (3,12)

a

QN=41 (8517) How we can understand about this statement: "All aggregate functions are deterministic"? a. This means aggregate functions return the same value any time they are called by using a specific set of input values b. This means aggregate functions return the different values each time they are called by using a specific set of input values c. This means aggregate functions return the same value any time they are called by using any set of input values d. None of the others

a

QN=42 (8518) Choose the correct statement a. Except for COUNT, aggregate functions ignore null values b. Except for SUM, aggregate functions ignore null values c. Except for AVG, aggregate functions ignore null values d. Except for MIN, aggregate functions ignore null values e. Except for MAX, aggregate functions ignore null values

?

QN=43 (8513) The table Arc(x,y) currently has the following tuples (note that there are duplicates): (1,2), (1,2), (2,3), (3,4), (3,4), (4,1), (4,1), (4,1), (4,2). Compute the result of the query: SELECT a1.x, a2.y, COUNT(*) FROM Arc a1, Arc a2 WHERE a1.y = a2.x GROUP BY a1.x, a2.y; Which of the following tuples is in the result? a. (3,1,2) b. (1,3,4) c. (2,4,6) d. (3,2,6)

a

QN=44 (8514) Column A of a relation has the following list of values in the six rows of the table: NULL, NULL, 10, 10, 20, 20 After grouping by (A+10), the output has: a. 3 groups b. 4 groups c. 2 groups d. 1 groups

c

QN=45 (8523) When we apply set operators (UNION, INTERSECT, EXCEPT) to two relations R and S, which conditions on R and S must be satisfied? a. R and S must have schemas with identical sets of attributes and the types (domains) for each attributes must be the same in R and S b. Before we compute the set-theoretic union, intersection, or difference of sets of tuples, the columns of R and S must be ordered so that the order of attributes is the same for both relations c. All of the others

b,d

QN=46 (8528) Suppose relation R(A,B) has the tuples: A B ------------------- 10 x 30 y 50 z 70 t and the relation S(B,C,D) has tuples: B C D ------------------------------------ x 40 60 z 60 80 z 50 50 z 70 90 Compute the right outer join of R and S, where the condition is: R.B = S.B. Then identify 2 tuples of R that do not appear in the computed result. a. (10,x) b. (30,y) c. (50,z) d. (70,t)

a

QN=47 (8537) What is a "join"? a. 'join' used to connect two or more tables logically with or without common field(s) b. 'join' used to connect two or more tables logically with common field(s) c. 'join' used to connect two or more tables logically without common field(s) d. 'join' used to connect two or more tables logically with aliases

a

QN=48 (8530) Suppose relation R(A,B) has the tuples: A B ------------------ 1 2 3 4 5 6 and the relation S(B,C,D) has tuples: B C D ----------------------------------- 2 4 6 4 6 8 4 7 9 Compute the outer-join of R and S, where the condition is: R.A>S.B AND R.B=S.C. Which of the following tuples of R or S is dangling (and therefore needs to be padded in the outer-join)? a. (4,7,9) of S. b. (2,4,6) of S. c. (4,6,8) of S. d. (3,4) of R.

a

QN=49 (8546) Relation R(x,y) currently consists of only one tuple (NULL, NULL). Which of the following queries will produce a nonempty output? That is, at least one tuple will be produced, although the tuple(s) may have NULL's. a. SELECT * FROM R WHERE x IS NULL b. SELECT * FROM R WHERE x = NULL c. SELECT * FROM R WHERE x = y d. SELECT * FROM R WHERE x <> 10

a

QN=5 (6809) A database administrator (DBA) is a person that is also known by the title: a. Database Coordinator or Database Programmer b. Database Tuner c. Database Analyst d. Database Modeller

a

QN=50 (8542) What does NULL mean? a. The value NULL means UNKNOWN b. The value NULL means '' (empty string) c. The value NULL means ' ' (space character) d. The value NULL means ZERO

a

QN=51 (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

c

QN=52 (8549) Choose one right answer. a. Arithmetic operators on NULL values will return a NULL value b. Comparisons with NULL values will return UNKNOWN c. All of the others. d. NULL value is unknown, inapplicable

a

QN=53 (8543) (TRUE AND NULL) returns: a. NULL b. TRUE c. FALSE d. None of the others

a

QN=54 (8557) Which SQL keyword is used to sort the result-set? a. ORDER BY b. SORT BY c. ORDER d. SORT

a

QN=55 (8558) Three properties of a lock in DBMS are: a)Granularity: the size of the lock b) Granularity: the type of the lock c) Mode: the type of the lock d) Duration: the time in seconds that the DBMS waits for a lock to be released a. (a) and (c) and (d) are true b. (a) and (b) and (d) are true c. (b) and (c) and (d) are true d. (a) and (b) and (c) are true

d

QN=56 (8564) Regardless of whatever any other transaction is doing, a transaction must be able to continue with the exact same data set it started with. The above describes which property of a transaction? a. Atomic b. Isolation c. Consistency d. Durability

c

QN=57 (8563) Every row and value must agree with all constraints right after the transaction is complete. The above describes which property of a transaction? a. Atomic b. Isolation c. Consistency d. Durability

a

QN=58 (8571) The latest scores from the Japanese Baseball League are in the table with schema Scores(Team, Opponent, RunsFor, RunsAgainst) The data in this table is as follows: Team Opponent RunsFor RunsAgainst --------------------------------------------------------------------------------------------------- Dragons Tigers 5 3 Carp Swallows 4 6 Bay Stars Giants 2 1 Marines Hawks 5 3 Ham Fighters Buffaloes 1 6 Lions Golden Eagles 8 12 Tigers Dragons 3 5 Swallows Carp 6 4 Giants Bay Stars 1 2 Hawks Marines 3 5 Buffaloes Ham Fighters 6 1 Golden Eagles Lions 12 8 Suppose we would like to executethe following query: SELECT Team, Opponent FROM Scores WHERE Team LIKE '% %' OR Opponent LIKE '_i%' Identify, in the list below, a row of the result. a. (Golden Eagles, Lions) b. (Hawks, Marines) c. (Giants,Bay Stars) d. (Swallows, Carp)

c

QN=59 (8576) The IN SQL keyword a. Is used with the DISTINCT SQL keyword only b. Is used with the INSERT SQL keyword only c. Determines if a value matches any of the values in a list or a sub-query d. Defines the tables we are selecting or deleting data from

d

QN=6 (6818) Which of the followings is part of data model? a. Structure of the data b. Operations on the data c. Constraints on the data d. All of the others

a

QN=60 (8567) What does the keyword ESCAPE mean? a. The keyword ESCAPE is used to match any string that contains the characters "%" or "_" b. There is no keyword named ESCAPE c. The keyword ESCAPE is used to match any string that contains the characters "?" or "*" d. The keyword ESCAPE is used to match any string that contains the characters "@" or "$"

b

QN=7 (6815) Which is the subset of SQL commands used to manipulate Database structures, including tables? a. DDL (Data Definition Language) b. DML (Data Manipulation Language) c. DCL (Data Control Language) d. All of the others

a

QN=8 (6822) Which statement is used to add a column named D into the relation R? a. ALTER TABLE R ADD D [DataType]; b. ALTER TABLE R ADD ATTRIBUTE D [DataType]; c. ALTER TABLE R ADD PROPERTY D [DataType];

a

QN=9 (6827) A _____ is a language for defining data structures a. DDL b. DML c. DCL d. None of the others