Database Concepts Exam 1
Real World Entity
A modern DBMS is more realistic uses real world entities to design its architecture
Attribute
A property or characteristic of an entity that has values
Which of the following describe logical data independence? Select all that apply. A) changes on table format should not change the data residing on the disk B) a kind of mechanism, which liberalizes itself from actual data C) Data about database D) it stores information about how data is managed inside
A) changes on table format should not change the data residing on the disk B) a kind of mechanism, which liberalizes itself from actual data
Application (Middle) Tier
At this tier reside the application and the programs that access the database
ACID Properties
Atomicity, Consistency, Isolation, Durability
Which of the following describe a database instance? Select all that apply A) does not contain any data or information B) a state of operational database with data at any given time C) contains a snapshot of the database D) the skeleton of database
B) a state of operational database with data at any given time C) contains a snapshot of the database
Which of the following describe logical data? Select all that apply. A) changes on table format should not change the data residing on the disk B) data about database C) a kind of mechanism, which liberalizes itself from actual data D) it stores information about how data is managed inside
B) data about database D) it stores information about how data is managed inside
Which of the following describes the Logical Database Schema? Select all that apply. A) defines how the data will be stored in a secondary storage B) defines all the logical constraints that need to be applied on the data stored C) defines tables, views, and integrity constraints D) pertains to the actual storage of data and its form of storage like files, indices, etc
B) defines all the logical constraints that need to be applied on the data stored C) defines tables, views, and integrity constraints
Which of the following describe a database schema? Select all that apply. A) contains a snapshot of the database B) defines how the data is organized C) is the skeleton structure that represents the logical view of the entire database D) DBMS ensures that its every instance (state) is in a valid state E) defines its entities and the relationship among them
B) defines how the data is organized C) is the skeleton structure that represents the logical view of the entire database E) defines its entities and the relationship among them
Which of the following describes the Physical Database Schema? Select all that apply. A) defines tables, views, and integrity constraints B) pertains to the actual storage of data and its form of storage like files, indices, etc C) defines all the logical constraints that need to be applied on the data stored D) defines how the data will be stored in a secondary storage
B) pertains to the actual storage of data and its form of storage like files, indices, etc D) defines how the data will be stored in a secondary storage
Consistency
Consistency is a state where every relation in a database remains constant
Relation-based tables
DBMS allows entities and relations among them to form tables
Less redundancy
DBMS follows the rules of normalization, which splits a relation when any of its attributes is having redundancy in values
Query Language
DBMS is equipped with query language, which makes it more efficient to retrieve and manipulate data
Multiuser and Concurrent Access
DBMS supports multi-user environment and allows them to access and manipulate data in parallel
While formulating real-world scenario into the database model, the ER Model creates all of the following EXCEPT? <relationship set, general attributes, data, constraints, entity set>
Data
User (Presentation) Tier
End-users operate on this tier
Designers
Group of people who actually work on the designing part of the database
Which of the following is NOT true regarding 2-tier architecture?
It is the most widely used architecture to design a DBMS
Many-to-one
More than one entities from entity set A can be associated with at most one entity of entity set B
Degree of relationship
Number of participating entities in a relationship
Many-to-many
One entity from A can be associated with more than one entity from B and vice versa
One-to-many
One entity from entity set A can be associated with more than one entities of entity set B however an entity from entity
Primary Key
One of the candidate keys
Entity
Real-world object that is identifiable
Data
Represents recordable facts
Super Key
Set of attributes that collectively identifies an entity
Which of the following does NOT define a data model?
Stored in a flat file
Database (Data) Tier
The database resides along with its query processing languages.
Multiple views
This feature enables the users to have a concentrate view of the database according to their requirements.
End Users
Those who actually reap the benefits of having a DBMS
Entity-Relationship (ER) Model is based on the notion of real-world entities and relationships among them. (True or False)
True
In the Relational Model attributes are also known as columns. (True or False)
True
In the Relational Model tables are also know as relations. (True or False)
True
In the Relational Model tuples are also known as records. (True or False)
True
Multi-value attributes may contain multiple values, such as tow or more phone numbers or email addresses. (True or False)
True
Single-value attributes contain single value. (True or False)
True
Which of the following is NOT part of the 3-tier Architecture?
View tier
Database Management Systems (DBMS)
a collection of interrelated data
entity set
a collection of similar types of entities
Isolation of data and application
a database is an active entity, where as data is said to be passive
Which of the following is NOT a valid mapping cardinality? <One to many, all to all, many to one, many to many, one to one>
all to all
Composite attribute
are made of more than one simple attribute
Simple attribute
atomic values, which cannot be divided further
Derived attribute
attributes that do not exist in the physical database, but their values are derived from other attributes
Database
collection of related data
Domain
data type
Mapping Cardinalities
define the number of association between the two entities
ER Model
defines the conceptual view of a database
Security
enables multiple users to have different views with different features
Which of the following is NOT true regarding 1-tier architecture?
it must have an application through which the DBMS can be accessed
Relationship
logical association among entities
Candidate Key
minimal super key
One-to-one
one entity from set A can be associated with at most one entity of entity set B and vice versa
Relationship Set
set of relationships of similar type
administrators
they are responsible to look after its usage and by whom it should be used