DBI202- part 6/7

Database integrity ensures that: a. data entered into the database is accurate, valid, and consistent b. data entered into the database is accurate, and consistent c. data entered into the database is valid, and consistent d. data entered into the database is accurate, and valid

a

Pay attention into the following query: SELECT * FROM R WHERE A LIKE '%a%'; So, in the above case, the wildcard % represents what? a. % (percent sign) represents zero, one, or more character b. % (percent sign) represents exactly 1 character

a

QN=31 (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

a

QN=42 (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=43 (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

a

QN=45 (8006) What is "normalization"? a. Normalizing data means eliminating redundant information from a table and organizing the data so that future changes to the table are easier b. Normalizing data means minimizing columns from a table and organizing the data so that future changes to the table will be made more quickly c. Normalizing data means removing columns from a table and organizing the data so that future changes to the table will be made more quickly d. Normalizing data means adding more columns to a table and organizing the data so that future changes to the table will be made more quickly

a

The SQL BETWEEN operator: a. Specifies a range to test. b. Specifies which tables we are selecting from. c. Specifies that a column is a primary key. d. None of the others

a

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 "$"

a

QN=32 (7981) Suppose we have a relation R(ABCD) with FD's: BC -> A ; AD -> C ; CD -> B ; BD -> C a. R is in BCNF b. R is not in BCNF c. All of the others d. None of the others

b

QN=38 (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

b

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

b

QN=40 (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

c

QN=44 (8007) Look at the following statements: (a)All relations in 3NF are also in 2NF (b)All relations in 2NF are also in 1NF (c)All relations in 1NF are also in BCNF (d)All relations in 1NF are also in 3NF a. (b) and (d) are true b. (a) and (c) are true c. (a) and (d) are true d. (a) and (b) are true

d

QN=46 (7997) Which of the following are guidelines for designing the relational schema ? a. Reduce the redundant values in tuples b. Reduce the NULL values in tuples c. Always make relations 3NF d. All of the others

d

Referential integrity Constraints control relationships between .... a. attributes in a table b. operations of an object c. database instances d. tables in a database

d

Which of the following statements is the most correct? a. Poorly designed indexes and a lack of indexes are primary sources of database application bottlenecks. b. Designing efficient indexes is paramount to achieve good database and application performance c. The selection of the right indexes for a database and its workload is a complex balancing act between query speed and update cost d. All of the others

d

With SQL, how do you select all the records from a table named "Persons" where the value of the column "FirstName" starts with an "a"? a. SELECT * FROM Persons WHERE FirstName='a' b. SELECT * FROM Persons WHERE FirstName LIKE '%a' c. SELECT * FROM Persons WHERE FirstName='%a%' d. SELECT * FROM Persons WHERE FirstName LIKE 'a%'

d