Database MCQ Set 1
1. Which of the following gives a logical structure of the database graphically ?
a) Entity-relationship diagram
b) Entity diagram
c) Database diagram
d) Architectural representation
Answer
Answer: a [Reason:] E-R diagrams are simple and clear—qualities that may well account in large part for the widespread use of the E-R model.
2. The entity relationship set is represented in E-R diagram as
a) Double diamonds
b) Undivided rectangles
c) Dashed lines
d) Diamond
Answer
Answer: d [Reason:] Dashed lines link attributes of a relationship set to the relationship set.
3. The Rectangles divided into two parts represents
a) Entity set
b) Relationship set
c) Attributes of a relationship set
d) Primary key
Answer
Answer: a [Reason:] The first part of the rectangle , contains the name of the entity set. The second part contains the names of all the attributes of the entity set.
4. Consider a directed line(->) from the relationship set advisor to both entity sets instructor and student. This indicates ___ cardinality
a) One to many
b) One to one
c) Many to many
d) Many to one
Answer
Answer: b [Reason:] This indicates that an instructor may advise at most one student, and a student may have at most one advisor.
5. We indicate roles in E-R diagrams by labeling the lines that connect _____ to ____
a) Diamond , diamond
b) Rectangle, diamond
c) Rectangle, rectangle
d) Diamond, rectangle
Answer
Answer: d [Reason:] Diamond represents a relationship set and rectangle represents a entity set.
6. An entity set that does not have sufficient attributes to form a primary key is termed a ____
a) Strong entity set
b) Variant set
c) Weak entity set
d) Variable set
Answer
Answer: c [Reason:] An entity set that has a primary key is termed a strong entity set.
7. For a weak entity set to be meaningful, it must be associated with another entity set, called the
a) Identifying set
b) Owner set
c) Neighbour set
d) Strong entity set
Answer
Answer: a [Reason:] Every weak entity must be associated with an identifying entity; that is, the weak entity set is said to be existence dependent on the identifying entity set. The identifying entity set is said to own the weak entity set that it identifies.It is also called as owner entity set.
8. Weak entity set is represented as
a) Underline
b) Double line
c) Double diamond
d) Double rectangle
Answer
Answer: c [Reason:] An entity set that has a primary key is termed a strong entity set.
9. If you were collecting and storing information about your music collection, an album would be considered a(n) _____
a) Relation
b) Entity
c) Instance
d) Attribute
Answer
Answer: b [Reason:] An entity set is a logical container for instances of an entity type and instances of any type derived from that entity type.
10. What term is used to refer to a specific record in your music database; for instance; information stored about a specific album?
a) Relation
b) Instance
c) Table
c) Column
Answer
Answer: b [Reason:] The environment of database is said to be instance. A database instance or an ‘instance’ is made up of the background processes needed by the database.
Database MCQ Set 2
1. An ________ is a set of entities of the same type that share the same properties, or attributes.
a) Entity set
b) Attribute set
c) Relation set
d) Entity model
Answer
Answer: a [Reason:] An entity is a “thing” or “object” in the real world that is distinguishable from all other objects.
2. Entity is a ___
a) Object of relation
b) Present working model
c) Thing in real world
d) Model of relation
Answer
Answer: c [Reason:] For example, each person in a university is an entity.
3. The descriptive property possessed by each entity set is ___
a) Entity
b) Attribute
c) Relation
d) Model
Answer
Answer: b [Reason:] Possible attributes of the instructor entity set are ID, name, dept name, and salary.
4. The function that an entity plays in a relationship is called that entity’s _______
a) Participation
b) Position
c) Role
d) Instance
Answer
Answer: c [Reason:] A relationship is an association among several entities.
5. The attribute name could be structured as a attribute consisting of first name, middle initial, and last name. This type of attribute is called
a) Simple attribute
b) Composite attribute
c) Multivalued attribute
d) Derived attribute
Answer
Answer: b [Reason:] Composite attributes can be divided into subparts (that is, other attributes).
6. The attribute AGE is calculated from DATE_OF_BIRTH . The attribute AGE is
a) Single valued
b) Multi valued
c) Composite
d) Derived
Answer
Answer: d [Reason:] The value for this type of attribute can be derived from the values of other related attributes or entities.
7. Not applicable condition can be represented in relation entry as
a) NA
b) 0
c) NULL
d) Blank Space
Answer
Answer: c [Reason:] NULL always represents that the value is not present.
8. Which of the following can be a multivalued attribute ?
a) Phone_number
b) Name
c) Date_of_birth
d) All of the mentioned
Answer
Answer: a [Reason:] Name and Date_of_birth cannot hold more than 1 value.
9. Which of the following is a single valued attribute
a) Register_number
b) Address
c) SUBJECT_TAKEN
d) Reference
Answer
Answer: a [Reason:] None.
10. In a relation between the entities the type and condition of the relation should be specified . That is called as______attribute.
a) Desciptive
b) Derived
c) Recursive
d) Relative
Answer
Answer: a [Reason:] Consider the entity sets student and section, which participate in a relationship set takes. We may wish to store a descriptive attribute grade with the relationship to record the grade that a student got in the class.
Database MCQ Set 3
1. Pictorial representation of an expression is called
a) Expression tree
b) Operator tree
c) Expression flow
d) Expression chart
Answer
Answer: b [Reason:] The operator tree has a tree like format where the evaluation starts from root of the tree .
2. The results of each intermediate operation are created and then are used for evaluation of the next-level operations. This is called
a) Materialized evaluation
b) Expression evaluation
c) Tree evaluation
d) Tree materialization
Answer
Answer: a [Reason:] The cost of a materialized evaluation is not simply the sum of the costs of the operations involved .
3. ________ allows the algorithm to execute more quickly by performing CPU activity in parallel with I/O activity.
a) Buffering
b) Double buffering
c) Multiple buffering
d) Double reading
Answer
Answer: a [Reason:] Double buffering using two buffers, with one continuing execution of the algorithm while the other is being written out .
4. Pipelines can be executed in
a) 4
b) 3
c) 2
d) 5
Answer
Answer: c [Reason:] Demand driven and producer driven pipelines are the two ways .
5. In a ___ the system makes repeated requests for tuples from the operation at the top of the pipeline.
a) Demand-driven pipeline
b) Producer-driven pipeline
c) Demand pipeline
d) All of the mentioned
Answer
Answer: a [Reason:] Each time that an operation receives a request for tuples, it computes the next tuple (or tuples) to be returned, and then returns that tuple .
6. In a _______ operations do not wait for requests to produce tuples, but instead generate the tuples eagerly.
a) Demand-driven pipeline
b) Producer-driven pipeline
c) Demand pipeline
d) All of the mentioned
Answer
Answer: b [Reason:] Each operation in a producer-driven pipeline is modeled as a separate process or thread within the system that takes a stream of tuples from its pipelined inputs and generates a stream of tuples for its output.
7. Each operation in a demand-driven pipeline can be implemented as an ____ that provides the following functions: open(), next(), and close().
a) Demand
b) Pipeline
c) Iterator
d) All of the mentioned
Answer
Answer: c [Reason:] After a call to open(), each call to next() returns the next output tuple of the operation.
8. The iterator maintains the ____ of its execution in between calls, so that successive next() requests receive successive result tuples.
a) State
b) Transition
c) Rate
d) Block
Answer
Answer: a [Reason:] The function close() tells an iterator that no more tuples are required.
9. Tuples are generated _____ in producer-driven pipelining, they are generated ________ on demand, in demand-driven pipelining.
a) Lazily, Eagerly
b) Eagerly, Lazily
c) Slowly, Eagerly
d) Eagerly, Slowly
Answer
Answer: b [Reason:] Producer-driven pipelining is very useful in parallel processing systems.
10. When two inputs that we desire to pipeline into the join are not already sorted it is the _______ technique.
a) Hash join
b) Buffer join
c) double-pipelined hash join
d) double-pipelined join
Answer
Answer: d [Reason:] When hash indices are used on tuples, the resultant algorithm is called the double-pipelined hash-join technique..
Database MCQ Set 4
1. The entity set person is classified as student and employee. This process is called ___
a) Generalization
b) Specialization
c) Inheritance
d) Constraint generalization
Answer
Answer: b [Reason:] The process of designating subgroupings within an entity set is called specialization.
2. Which relationship is used to represent a specialization entity ?
a) ISA
b) AIS
c) ONIS
d) WHOIS
Answer
Answer: a [Reason:] In terms of an E-R diagram, specialization is depicted by a hollow arrow-head pointing from the specialized entity to the other entity.
3. The refinement from an initial entity set into successive levels of entity subgroupings represents a ________ design process in which distinctions are made explicit.
a) Hierarchy
b) Bottom-up
c) Top-down
d) Radical
Answer
Answer: c [Reason:] The design process may also proceed in a bottom-up manner, in which multiple entity sets are synthesized into a higher-level entity set on the basis of common features.
4. There are similarities between the instructor entity set and the secretary entity set in the sense that they have several attributes that are conceptually the same across the two entity sets: namely, the identifier, name, and salary attributes. This process is called
a) Commonality
b) Specialization
c) Generalization
d) Similarity
Answer
Answer: c [Reason:] Generalization is used to emphasize the similarities among lower-level entity sets and to hide the differences.
5. If an entity set is a lower-level entity set in more than one ISA relationship, then the entity set has
a) Hierarchy
b) Multilevel inheritance
c) Single inheritance
d) Multiple inheritance
Answer
Answer: d [Reason:] The attributes of the higher-level entity sets are said to be inherited by the lower-level entity sets.
6. A _______ constraint requires that an entity belong to no more than one lower-level entity set.
a) Disjointness
b) Uniqueness
c) Special
d) Relational
Answer
Answer: a [Reason:] For example, student entity can satisfy only one condition for the student type attribute; an entity can be either a graduate student or an undergraduate student, but cannot be both.
7. Consider the employee work-team example, and assume that certain employees participate in more than one work team . A given employee may therefore appear in more than one of the team entity sets that are lower level entity sets of employee. Thus, the generalization is _______
a) Overlapping
b) Disjointness
c) Uniqueness
d) Relational
Answer
Answer: a [Reason:] In overlapping generalizations, the same entity may belong to more than one lower-level entity set within a single generalization.
8. The completeness constraint may be one of the following: Total generalization or specialization , Partial generalization or specialization . Which is the default ?
a) Total
b) Partial
c) Should be specified
d) Cannot be determined
Answer
Answer: b [Reason:] Partial generalization or specialization – Some higher-level entities may not belong to any lower-level entity set.
9. Functional dependencies are a generalization of
a) Key dependencies
b) Relation dependencies
c) Database dependencies
d) None of the mentioned
Answer
Answer: a [Reason:] The subclasses are combined to form the superclass.
10. Which of the following is another name for weak entity?
a) Child
b) Owner
c) Dominant
d) All of the mentioned
Answer
Answer: a [Reason:] A parent may be called as a strong entity.
Database MCQ Set 5
1. The recovery scheme must also provide
a) High availability
b) Low availability
c) High reliability
d) High durability
Answer
Answer: a [Reason:] It must minimize the time for which the database is not usable after a failure.
2. Which one of the following is a failure to system
a) Boot crash
b) Read failure
c) Transaction failure
d) All of the mentioned
Answer
Answer: c [Reason:] Types of system failure are transaction failure, system crash and disk failure.
3. Which of the following belongs to transaction failure
a) Read error
b) Boot error
c) Logical error
d) All of the mentioned
Answer
Answer: c [Reason:] Types of system transaction failure are logical and system error.
4. The system has entered an undesirable state (for example, deadlock), as a result of which a transaction cannot continue with its normal execution. This is
a) Read error
b) Boot error
c) Logical error
d) System error
Answer
Answer: c [Reason:] The transaction, can be re-executed at a later time.
5. The transaction can no longer continue with its normal execution because of some internal condition, such as bad input, data not found, overflow, or resource limit exceeded. This is
a) Read error
b) Boot error
c) Logical error
d) System error
Answer
Answer: c [Reason:] The transaction, can be re-executed at a later time.
6. The assumption that hardware errors and bugs in the software bring the system to a halt, but do not corrupt the nonvolatile storage contents, is known as the
a) Stop assumption
b) Fail assumption
c) Halt assumption
d) Fail-stop assumption
Answer
Answer: d [Reason:] Well-designed systems have numerous internal checks, at the hardware and the software level, that bring the system to a halt when there is an error. Hence, the fail-stop assumption is a reasonable one.
7. Which kind of failure loses its data in head crash or failure during transfer operation.
a) Transaction failure
b) System crash
c) Disk failure
d) All of the mentioned
Answer
Answer: c [Reason:] Copies of the data on other disks, or archival backups on tertiary media, such as DVD or tapes, are used to recover from the failure.
8. The failure occurred sufficiently early during the transfer that the destination block remains intact.
a) Partial Failure
b) Total failure
c) Successful completion
d) Data transfer failure
Answer
Answer: a [Reason:] Copies of the data on other disks, or archival backups on tertiary media, such as DVD or tapes, are used to recover from the failure.
9. The database is partitioned into fixed-length storage units called
a) Parts
b) Blocks
c) Reads
d) Build
Answer
Answer: b [Reason:] Blocks are the units of data transfer to and from disk, and may contain several data items.
10. Which of the following causes system to crash
a) Bug in software
b) Loss of volatile data
c) Hardware malfunction
d) All of the mentioned
Answer
Answer: d [Reason:] The content of non-volatile storage remains intact, and is not corrupted.
