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WorksheetsDBMS CA1-2025-26
Total questions: 20
Worksheet time: 20mins
What is the difference between a strong entity and a weak entity?
A strong entity has no primary key and is dependent on a weak entity.
Both strong and weak entities have primary keys and can exist independently.
A weak entity can exist independently and has a primary key.
A strong entity has a primary key and can exist independently; a weak entity depends on a strong entity and does not have a primary key.
Define cardinality in the context of relationships in ER models.
Cardinality defines the attributes of an entity in an ER model.
Cardinality indicates the primary key of an entity in an ER model.
Cardinality refers to the number of instances of one entity that can or must be associated with instances of another entity in an ER model.
Cardinality is the total number of entities in an ER model.
Explain the concept of keys in a relational schema.
Keys are only used for indexing data in a database.
Keys in a relational schema are always numeric values.
Foreign keys are used to delete records from a table.
Keys in a relational schema are attributes that uniquely identify records, including primary keys and foreign keys.
What is the purpose of generalization in the EER model?
To define relationships between unrelated entities.
The purpose of generalization in the EER model is to abstract common features of multiple entities into a single entity.
To create multiple entities from a single entity.
To eliminate redundancy in the database design.
Describe the process of mapping an ER model to a relational model.
Using only primary keys without foreign keys
The process of mapping an ER model to a relational model involves creating tables for entities, defining primary keys, mapping attributes to columns, establishing foreign keys for relationships, creating junction tables for many-to-many relationships, and normalizing the tables.
Creating a single table for all entities
Ignoring normalization in the design process
What are the main operators used in relational algebra?
Selection, Projection, Union, Set Difference, Cartesian Product, Rename
Join, Intersection, Division
Aggregation, Sorting, Filtering
Grouping, Summation, Average
How does specialization differ from generalization in the EER model?
Specialization creates sub-entities from a general entity, while generalization combines entities into a general entity.
Specialization only applies to attributes, while generalization applies to relationships.
Specialization and generalization are identical processes in the EER model.
Specialization combines entities into a general entity, while generalization creates sub-entities from a general entity.
Provide an example of a relational algebra query.
ρ_newName/oldName(Employees)
γ_department, COUNT(*)(Employees)
σ_department='Sales'(Employees)
π_name(Employees)
What is aggregation in the context of the EER model?
Aggregation is a higher-level entity that represents a relationship between entities in the EER model.
Aggregation refers to the process of summarizing data in reports.
Aggregation is a method for data normalization in databases.
Aggregation is a type of data encryption used in security.
If you want to maintain and store information about your car inurance company, a car would be considered a(n) _____
Relation
Entity
Instance
Attribute
What is the purpose of the SELECT operation in relational algebra?
Combine rows from different tables
Filter rows based on a condition
Add new records to a table
Sort the table in ascending order
Which additional relational algebra operation is used to combine rows from two tables?
Union
Join
Project
Intersect
Here which of the following displays the unique values of the column?
SELECT ________ dept_name
FROM instructor;
from
like
unique
distinct
What is the difference between INNER JOIN and LEFT JOIN in SQL?
INNER JOIN returns matching rows from both tables; LEFT JOIN returns all rows from the left table and matched rows from the right table.
INNER JOIN returns all rows from both tables; LEFT JOIN returns only unmatched rows from the left table.
INNER JOIN includes all rows from the right table; LEFT JOIN excludes unmatched rows from the left table.
INNER JOIN returns all rows from the left table; LEFT JOIN returns only matching rows from both tables.
Which of the following is not a function of a DBMS?
Data storage
Data retrieval
Data manipulation
Data transmission
In a Flat File System, data redundancy refers to:
The ability to store multiple copies of the same file
The repetition of the same data within a single file
The inability to store data in separate files
The lack of data indexing capabilities
Which level of data abstraction describes how the data are stored in the database?
Physical level
Logical Level
View Level
All the Above
Which of the following is not a DBMS
