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DBI202 Final Exam |Questions with 100% Correct Answers
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DBI202 Final Exam |Questions with 100% Correct Answers
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DBI202 Final Exam |Questions with 100%Correct Answers
Which of the following expression is equivalent to the intersection of R and S:
Select one:
a. R - S
b. S - (R - S)
c. R - (S - R)
d. R - (R - S) - ✔ ✔ d
With SQL, how do you select all the records from a table named "Persons" where
the "LastName" is alphabetically between (and including) "Nguyen" and "Tran"?
Select one:
a. SELECT LastName>'Nguyen' AND LastName<'Tran' FROM Persons
b. SELECT * FROM Persons WHERE LastName>'Nguyen' AND LastName<'Tran'
c. None of the others.
d. SELECT * FROM Persons WHERE LastName BETWEEN 'Nguyen' AND 'Tran' - ✔ ✔ d
Which of the followings has the same meaning as referential integrity constraint?
Select one:
a. Foreign key constraint
b. Attribute based constraint
,c. Tuple based constraint
d. Entity based constraint - ✔ ✔ a
An attribute A is called the key of relation R if __________
Select one:
a. Its closure includes all attributes of relation R
b. It functionally determines all the other attributes of relation R
c. There are no two tuples that have the same values on the A component
d. All of the others - ✔ ✔ d
Which of the followings is right about DML ?
Select one or more:
a. All of the others
b. Use to retrieve, insert, update, and delete
c. No affect on the content of the database or extract data from
database d. No affect on the schema of the database - ✔ ✔ b, d
suppose that :
-A relation Movies(ID, name, type)
-ID is a key attribute and name, type are not key
attributes - t1, t2 are two instances of Movies
What relation algebra is used to express a key constraint on Movies?
Select one:
a. st1.ID¹t2.ID AND t1.name=t2.name AND t1.type=t2.type (t1 x t2)=Æ
b. t1.ID=t2.ID AND t1.name¹t2.name AND t1.type¹t2.type (t1 x t2)=Æ
c. st1.ID=t2.ID AND t1.name=t2.name AND t1.type=t2.type (t1 x t2)=Æ
d. st1.ID¹t2.ID AND t1.name¹t2.name AND t1.type¹t2.type (t1 x t2)=Æ - ✔ ✔ b
, Choose a right statement to describe about functional dependency.
Select one:
a. all of others
b. constraints between two sets of attributes of a
relation c. a functional dependency is written like X->Y
d. A set of attributes X (A1,A2,..,An) in R determines another set of attributes Y also in R if and
only if each X value is associated with precisely one Y value. - ✔ ✔ a
Which of the followings evolves to information integration?
Select one:
a. None of the others
b. Datawarehouse
c. Database
d. Online Analytical Processing - ✔ ✔ b
Which of the following statements can be used in PSM's body?
Select one:
a. Update statement
b. Delete statement
c. Insert statement
d. All of the others - ✔ ✔ d
Which of the following constructs can be used in PSM?
Select one or more:
a. FOR ... DO ...
b. WHILE .... DO ...
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