Introduction and ER Model MCQ Quiz - Objective Question with Answer for Introduction and ER Model - Download Free PDF

Concept:

The correct answer is Multi-valued Attribute.

Key Points

• A Multi-valued Attribute in an Entity-Relationship (ER) diagram is an attribute that can hold multiple values for a single entity.
  • In an ER diagram, a multi-valued attribute is represented by a double ellipse.
  • For example, a person entity might have a multi-valued attribute "Phone Numbers" because a person can have more than one phone number.
  • Multi-valued attributes are used to represent situations where an entity can have multiple instances of the same attribute.
  • These attributes are essential for accurately modeling real-world scenarios where entities can possess multiple values for a particular attribute.
  • Proper representation of multi-valued attributes helps in designing a normalized database schema.

Additional Information

• In database design, it's often necessary to create a separate table to handle multi-valued attributes to maintain normalization.
• Entity-Relationship diagrams are a vital tool for database design as they help visualize the relationships between different entities.
• Understanding how to represent different types of attributes in an ER diagram is crucial for designing efficient and accurate databases.
• Other attribute types in ER diagrams include simple attributes (represented by a single ellipse) and composite attributes (represented by an ellipse containing other ellipses).

The correct answer is Option 2.

Key Points

• A RDBMS (Relational Database Management System) stores data in related tables.
• A Primary Key is used for the unique identification of tuples in a table.
• A Tuple is a collection of attribute values.
• A Database Schema and Constraints are stored in the database catalog.

Additional Information

• RDBMS examples include MySQL, PostgreSQL, and Oracle.
• A primary key ensures that each record in a table is unique and can be referenced from other tables.
• In databases, a tuple is equivalent to a row in a table, and it contains a set of values for each attribute.
• The database catalog contains metadata about the database schema, including tables, columns, data types, and constraints.

The correct answer is Python or DBMS like Mysql.

Key Points

• Python or DBMS like Mysql are effective methods for storing and retrieving data.
  • Python provides various libraries and frameworks such as SQLite, SQLAlchemy, and Pandas for database operations.
  • DBMS (Database Management Systems) like MySQL offer robust solutions for data storage, retrieval, and management.
  • Both methods can handle large amounts of data efficiently and support complex queries and transactions.
  • Python is known for its simplicity and ease of use, making it a popular choice for beginners and experts alike.
  • MySQL is a widely used open-source RDBMS known for its reliability and performance in handling large-scale applications.

Additional Information

• Python can also interface with other databases like PostgreSQL, MongoDB, and Oracle.
• DBMS systems provide features like data integrity, security, and backup solutions.
• MySQL supports various data types and indexing for optimized performance.
• Python's SQLAlchemy is an ORM (Object-Relational Mapping) library that simplifies database operations by mapping database schemas to Python objects.

The correct answer is: option 4.

 Key PointsPre-processing Steps in Procuring Data:
These are the actions performed on data before it is used for analysis, storage, or decision-making.

According to the paragraph, the pre-processing steps include:

1. Store

Meaning: Saving the data to a storage device like a hard disk, cloud storage, or database.

Purpose: To ensure the data is available for future use.

2. Retrieve
Meaning: Getting or fetching the stored data from storage when needed.

Purpose: Allows users or systems to access data for processing or analysis.

3. Classify
Meaning: Organizing or categorizing the data into groups or types (e.g., structured or unstructured).

Purpose: Makes it easier to analyze and process the data.

4. Update
Meaning: Modifying the existing data by adding, changing, or deleting values.

Purpose: Keeps data accurate and up to date.

❌ What is not included:
Search: Although it's a common data operation, it is not listed in the paragraph as a pre-processing step.

✅ Conclusion:
Pre-processing prepares raw data into a usable format by storing, retrieving, classifying, and updating it — making it ready for effective analysis or use in applications.

Rules for finding a minimum number of tables required for an ER diagram:

1) A strong entity with single or composite attributes requires one table.

2) A strong entity with multivalued attributes requires two tables.

3) In the case of many to many relations between two entities, 3 tables are required.

Explanation:

There is one to many relationships between R₁and R₂. So, two tables are required for two entities. But, entity R₁ contains multivalued attribute B, due to which one table for this is also needed.

Here we have 1 to Many relation so we requires two tables.

Attribute B being multi-valued, we need to remove the multi-valued attribute B to convert the given entity-relationship diagram into a relational database.

As relational database do not allow multi-valued attributes. We have to introduce a new table.

So, the number of tables is as below:
R1
R12R2
A table for B (Multi-valued attribute)
So, a total of 3 tables are required for the given entity relational diagram.

So, option 3 is the correct answer.

Concept:

An attribute that can be derived from other attributes of the entity type is known as a derived attribute, derived attribute is represented by a dashed eclipse.

Explanation:

In the ER model,

Option 1: Double ellipse

Multivalued attribute

Option 2: Dashed ellipse

Derived attribute

Option 4: Ellipse with attribute name underlined

Key attribute

Concept:

Total participation: It specifies that each entity in the entity set must compulsorily participate in at least one relationship instance in that relationship set.

Partial participation: It specifies that each entity in the entity set may or may not participate in the relationship instance in that relationship set.

Explanation:

In one to many or many to one relation, the relation between two entities is merged on the many side with total participation. As, it is given that relationship R doesn’t have its own attributes. So, it must be combined with entity A. So, the relation must be many to one and there should be total participation of A in R.

The correct answer is "option 3".

EXPLANATION:

On converting the given ER diagram into the relational table, we will get three tables -

Hence, Exam (ExamID, NID, ExamName) is not a possible relation.

Concept: 

An entity set which has determined an attribute or set of attributes to be a primary key is called a strong entity set.

If an entity set does not have enough attributes to form a primary key, it is called a weak entity set.

Explanation:

In E-R diagram, the many-to-one relationship with a weak entity set is represented by diamond with double borders.

Important Point:

The relationship with weak entity set would be represented by diamonds with double/bold borders.

The weak entity set itself would be represented by rectangle with double/bold border.

Concept:

The correct answer is option 4.

Concept:

A relational database management system (RDBMS) is a collection of programs and capabilities that enable IT teams and others to create, update, administer and otherwise interact with a relational database.

Domain Constraints:

Domain Constraints are user-defined columns that help the user to enter the value according to the data type. Columns are called attributes of a relation. It is also called an attribute constraint.

Hence the correct answer is attribute constraint.

Additional Information There are two types of constraints that come under domain constraint and they are:

Domain Constraints Not Null:

Null values are the values that are unassigned or we can also say that which are unknown or the missing attribute values and by default, a column can hold the null values.

Example:

Create table employee (employee_id varchar(30), employee_name varchar(30) not null, salary NUMBER);

Domain Constraints Check:

It defines a condition that each row must satisfy which means it restricts the value of a column between ranges or we can say that it is just like a condition or filter checking before saving data into a column.

Example:

Create table employee (employee_id varchar(30) not null check(employee_id > 0), employee_name varchar(30), salary NUMBER);

The correct answer is Secondary storage.

Key Points

• Secondary storage:
  • It is also referred to as auxiliary storage, is non-volatile, and is used for later retrieval to store data and programs.
  • There are several forms of secondary storage, each with benefits and drawbacks.
  • Either magnetic or optical storage media are used for most storage systems.
  • The hard disk is an example of secondary storage and magnetic media, which is used for storing data and programs in bulk. Hence, Option 4 is correct.
  • In the case of the computer, they are normally in-built and therefore are not portable.
  • Some hard drives are reversible, so between machines, they provide easy portable storage.
  • In general, they are efficient and stable, with easy access to stored data.
  • This allows the disk to rotate at even greater speeds than it would otherwise do without distorting the disk surface.

Additional Information Difference between Primary and Secondary memory:

Concept:

Three level architecture is a framework for describing database concepts and specifying the structure of the database system. Three levels are the external level, conceptual level, and internal level.

Explanation:

Internal level: 

It describes the actual physical storage of data or the way in which the data is actually stored in memory. It is not relational because data is stored according to various coding schemes instead of tabular form. 

Conceptual level: 

It is also known as a logical level. It is relational because data visible at will be relational tables. It represents the entire contents of the database in an abstract form. It hides the actual physical storage and concentrates on the relational model of the database.

External level: 

It is concerned with individual users. It describes the actual view of data seen by individual users. It is defined by DBA for every user. Users can only access data for which he is authorized by DBA.

The three components of the three-level RDBMS architecture are:

Conceptual level: This level describes the overall structure of the database. It includes entities, attributes, and relationships, which define the data to be stored in the database.
Internal level: This level describes how the data is stored on disk, including details about physical storage, indexing, and other storage-dependent details.
External level: This level describes how users interact with the database. It includes semantic information, such as constraints and authorization information, that controls how data can be accessed and updated.
 In summary, the conceptual level describes the database at a high level, while the internal and external levels describe the database at lower levels of detail, focusing on storage and user interaction respectively.

Concept:

A relation is in 3NF for every functional dependency if X -> A  and one of the following condition holds true .

1) X is a superkey  or

2) A is a prime attribute.

Explanation:

E₁ has attributes a₁₁ and a₁₂. a₁₁ is the primary key.

Entity E₂ has attributes a₂₁ and a₂₂ where a₂₁ is the primary key.

Entity E₃ has attributes a₃₁ and a₃₂ where a₃₁ is the primary key.

R₁₂ is many to many relationship between E₁ and E₂. So, R₁₂ contains attributes a₁₁ and a_21.

R₁₃ is a one to many relationship between E₁ and E_3. R₁₃ contains attributes a₁₁ and a₃₁

In this we have 5 tables 3 for three entities and 2 for two relation.

But we have to find minimum number of tables or relations considering if all the relations are in 3 NF.

Here, we have to keep a separate table for R₁₂ because if we combine it with any other relation it will violates 1 NF and hence 3NF. Because it will contain composite key since it is a many to many relation.

But we can combine relation R₁₃ with entity E₃.

R₁₃E₃ (a₁₁, a₃₁, a₃₂)

It will not violates 3 NF . Because here a_11, a₃₁, a₃₂ is the key.  Here, it will not create any partial dependency. Hence it satisifies 3NF.

So, minimum 4 relations are required here.