1What is the primary disadvantage of using a File Processing System compared to a DBMS regarding data storage?
A.Data Atomicity
B.Data Redundancy and Inconsistency
C.Data Isolation
D.Data Security
Correct Answer: Data Redundancy and Inconsistency
Explanation:In file processing systems, different programs may create separate files for specific tasks, leading to the same data being stored in multiple places (redundancy). This often results in data inconsistency where updates in one file are not reflected in others.
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2Which component of a DBMS is responsible for translating DML statements into low-level file system instructions?
A.Query Processor
B.DML Compiler
C.Data Dictionary
D.Transaction Manager
Correct Answer: DML Compiler
Explanation:The DML (Data Manipulation Language) Compiler translates DML statements into an evaluation plan comprising low-level instructions that the query evaluation engine understands.
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3In the Three-Schema Architecture, which level describes how the data is actually stored on the storage medium?
A.Conceptual Level
B.External Level
C.Physical (Internal) Level
D.Logical Level
Correct Answer: Physical (Internal) Level
Explanation:The Physical (or Internal) level describes the physical storage structure of the database, including complex low-level data structures and file organizations.
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4What is Physical Data Independence?
A.The ability to change the conceptual schema without changing the external schema.
B.The ability to change the physical schema without changing the conceptual schema.
C.The ability to change the external schema without changing the physical schema.
D.The ability to modify data without authorization.
Correct Answer: The ability to change the physical schema without changing the conceptual schema.
Explanation:Physical Data Independence is the capacity to change the internal schema (physical storage details) without having to change the conceptual schema (logical structure).
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5The collection of information stored in the database at a particular moment in time is known as a(n) ____.
A.Schema
B.Instance
C.Model
D.Relation
Correct Answer: Instance
Explanation:An instance is the actual content of the database at a specific point in time, analogous to the values of variables in a program at a specific moment.
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6Which of the following symbols is used to represent an Entity Set in an Entity-Relationship (ER) Diagram?
A.Ellipse
B.Diamond
C.Rectangle
D.Double Ellipse
Correct Answer: Rectangle
Explanation:In ER diagrams, a Rectangle represents an Entity Set. Ellipses represent attributes, and Diamonds represent relationship sets.
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7In the Relational Model, a row in a table represents a ____.
A.Domain
B.Schema
C.Tuple
D.Degree
Correct Answer: Tuple
Explanation:A row in a relational table is formally referred to as a Tuple, which represents a single record of data.
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8If a relation has 5 attributes and 10 tuples, what is the degree of relation ?
A.5
B.10
C.15
D.50
Correct Answer: 5
Explanation:The degree of a relation is defined as the number of attributes (columns) it contains. Since has 5 attributes, its degree is 5.
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9Which of the following is a characteristic of NoSQL databases compared to Relational databases?
A.Strict Schema Enforcement
B.Complex Joins Support
C.Horizontal Scaling
D.ACID Compliance as a primary focus
Correct Answer: Horizontal Scaling
Explanation:NoSQL databases are typically designed for Horizontal Scaling (adding more servers), whereas traditional relational databases rely more on vertical scaling (adding power to a single server).
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10What does a double ellipse represent in an ER Diagram?
A.Derived Attribute
B.Multivalued Attribute
C.Composite Attribute
D.Key Attribute
Correct Answer: Multivalued Attribute
Explanation:A double ellipse indicates a Multivalued Attribute, which is an attribute that can hold multiple values for a single entity (e.g., multiple phone numbers).
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11The Conceptual Schema is defined at which level of the 3-tier architecture?
A.View Level
B.Logical Level
C.Physical Level
D.Storage Level
Correct Answer: Logical Level
Explanation:The Conceptual Schema exists at the Logical Level. It describes what data is stored in the database and the relationships among those data, hiding physical storage details.
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12Which property ensures that a transaction is treated as a single, indivisible unit of work (all or nothing)?
A.Atomicity
B.Consistency
C.Isolation
D.Durability
Correct Answer: Atomicity
Explanation:Atomicity ensures that all operations of a transaction are reflected in the database properly, or none are. Partial updates are not allowed.
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13In an ER diagram, a Weak Entity Set must be associated with an identifying entity set via a relationship called a ____.
A.Identifying Relationship
B.Recursive Relationship
C.Ternary Relationship
D.Total Relationship
Correct Answer: Identifying Relationship
Explanation:A weak entity set does not have a primary key of its own and depends on the Identifying Relationship with a strong (identifying) entity set for existence.
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14Which of the following best describes Data Modeling?
A.The process of creating physical files on a disk.
B.Creating a conceptual representation of data objects and their relationships.
C.Writing SQL queries to retrieve data.
D.Installing the DBMS software.
Correct Answer: Creating a conceptual representation of data objects and their relationships.
Explanation:Data Modeling is the process of creating a visual or conceptual representation of the data objects, the associations between different data objects, and the rules.
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15In the relational model, the set of permitted values for each attribute is called the ____.
A.Range
B.Domain
C.Set
D.Group
Correct Answer: Domain
Explanation:A Domain is the set of atomic values that are permitted for a specific attribute (e.g., the domain of a 'GPA' attribute might be real numbers between 0.0 and 4.0).
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16What is Logical Data Independence?
A.Immunity of the external schemas to changes in the conceptual schema.
B.Immunity of the conceptual schema to changes in the physical schema.
C.Immunity of the physical schema to changes in the disk structure.
D.Immunity of the application to hardware failure.
Correct Answer: Immunity of the external schemas to changes in the conceptual schema.
Explanation:Logical Data Independence is the ability to change the conceptual schema (e.g., adding a new field) without changing the external schemas (views) or application programs.
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17Which symbol represents a Relationship Set in an ER diagram?
A.Rectangle
B.Ellipse
C.Diamond
D.Triangle
Correct Answer: Diamond
Explanation:In standard ER notation, a Diamond shape is used to represent a relationship set connecting entity sets.
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18A key that consists of more than one attribute to uniquely identify a tuple is called a ____.
A.Foreign Key
B.Composite Key
C.Simple Key
D.Domain Key
Correct Answer: Composite Key
Explanation:A Composite Key is a primary key composed of multiple attributes (columns) used together to create a unique identifier for a row.
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19Which of the following is NOT a typical application of a DBMS?
A.Airline Reservation Systems
B.Banking Systems
C.Real-time Operating System Kernel scheduling
D.University Student Management
Correct Answer: Real-time Operating System Kernel scheduling
Explanation:OS Kernel scheduling requires extremely low latency and hardware-level control, usually managed by data structures in memory, not a general-purpose DBMS.
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20In a Relational Database, a Foreign Key is used to:
A.Uniquely identify a record in the current table.
B.Establish a link between the data in two tables.
C.Store large binary objects.
D.Index the table for faster searching.
Correct Answer: Establish a link between the data in two tables.
Explanation:A Foreign Key is a field (or collection of fields) in one table that refers to the Primary Key in another table, establishing a relationship between the two.
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21The schema of a database is:
A.The data stored at a specific time.
B.The overall design or structure of the database.
C.The list of authorized users.
D.The physical disk arrangement.
Correct Answer: The overall design or structure of the database.
Explanation:The schema refers to the logical design and structure of the database, which rarely changes, as opposed to the instance which changes frequently.
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22Which attribute type in an ER diagram is represented by a dashed ellipse?
A.Composite Attribute
B.Multivalued Attribute
C.Derived Attribute
D.Key Attribute
Correct Answer: Derived Attribute
Explanation:A Derived Attribute (one that can be calculated from other attributes, like Age from DateOfBirth) is represented by a dashed ellipse.
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23What is the Cardinality of a relation?
A.The number of attributes in the relation.
B.The number of tuples (rows) in the relation.
C.The size of the relation in bytes.
D.The number of relationships it participates in.
Correct Answer: The number of tuples (rows) in the relation.
Explanation:In relational terminology, Cardinality refers to the number of tuples (rows) currently in the table.
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24In the context of the ER model, what does a Total Participation (indicated by a double line) mean?
A.Every entity in the entity set must participate in the relationship.
B.Only some entities participate in the relationship.
C.The relationship is many-to-many.
D.The entity set is weak.
Correct Answer: Every entity in the entity set must participate in the relationship.
Explanation:Total participation (indicated by double lines connecting the entity to the relationship) implies that every entity in that set is involved in at least one relationship instance.
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25Which of the following is an example of a Non-Relational (NoSQL) database?
A.MySQL
B.Oracle Database
C.MongoDB
D.PostgreSQL
Correct Answer: MongoDB
Explanation:MongoDB is a document-oriented NoSQL database. MySQL, Oracle, and PostgreSQL are Relational Database Management Systems (RDBMS).
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26The View Level in the 3-tier architecture allows:
A.Users to see the entire database structure.
B.Users to see only a part of the database relevant to them.
C.DBAs to optimize disk storage.
D.The system to perform backup operations.
Correct Answer: Users to see only a part of the database relevant to them.
Explanation:The View Level (External Level) provides a customized view of the data, hiding the rest of the database for security and simplification purposes.
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27A Super Key is:
A.A minimal set of attributes that uniquely identifies a tuple.
B.Any set of attributes that uniquely identifies a tuple.
C.A key used for encryption.
D.A key that relates two tables.
Correct Answer: Any set of attributes that uniquely identifies a tuple.
Explanation:A Super Key is a set of one or more attributes that, taken collectively, allows us to identify uniquely a tuple in the relation. A Candidate Key is a minimal Super Key.
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28Which constraint ensures that a Primary Key cannot contain NULL values?
A.Entity Integrity Constraint
B.Referential Integrity Constraint
C.Domain Constraint
D.Key Constraint
Correct Answer: Entity Integrity Constraint
Explanation:The Entity Integrity Constraint states that no primary key value can be NULL, as primary keys are used to uniquely identify individual tuples.
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29In data modeling, what is Metadata?
A.Large binary data.
B.Data about data.
C.Redundant data.
D.Corrupted data.
Correct Answer: Data about data.
Explanation:Metadata is 'data about data', such as the names of relations, names of attributes, data types, and constraints stored in the data dictionary.
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30Which notation represents a Many-to-One relationship from Entity A to Entity B in an ER diagram?
A.An arrow pointing to A.
B.An arrow pointing to B.
C.A generic line with no arrows.
D.Double lines on both sides.
Correct Answer: An arrow pointing to B.
Explanation:In standard ER notation (such as Korth/Silberschatz), an arrow pointing to an entity set indicates 'One'. If the arrow points to B, it means for one B there are many A's (Many-to-One from A to B).
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31Compared to Relational Databases, NoSQL databases are generally better suited for:
A.Complex transactional systems (Banking).
B.Unstructured or semi-structured data (Big Data).
C.Applications requiring strict ACID compliance.
D.Legacy systems relying on COBOL.
Correct Answer: Unstructured or semi-structured data (Big Data).
Explanation:NoSQL databases (like Document or Key-Value stores) offer flexible schemas, making them ideal for unstructured or semi-structured data often found in Big Data and real-time web apps.
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32The attribute that acts as the primary identifier in a relation is typically underlined in the ER model. What is it called?
A.Weak Key
B.Derived Attribute
C.Primary Key
D.Composite Attribute
Correct Answer: Primary Key
Explanation:The Primary Key is the attribute (or set of attributes) chosen to uniquely identify entities in an entity set, typically represented by underlining the attribute name in ER diagrams.
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33What is the mathematical definition of a Relation in the relational model?
A.A pointer to a file location.
B.A subset of the Cartesian product of a list of domains.
C.A linked list of data blocks.
D.A hierarchical tree structure.
Correct Answer: A subset of the Cartesian product of a list of domains.
Explanation:Mathematically, a relation on domains is a subset of the Cartesian product .
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34Which DBMS component manages the allocation of space on disk structures?
A.Transaction Manager
B.Storage Manager
C.Query Processor
D.Buffer Manager
Correct Answer: Storage Manager
Explanation:The Storage Manager is the component that provides the interface between the low-level data stored in the database and the application programs/queries submitted to the system. It handles disk space allocation.
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35What is a Composite Attribute?
A.An attribute that can be divided into sub-parts.
B.An attribute derived from another attribute.
C.An attribute that must be unique.
D.An attribute that holds multiple values.
Correct Answer: An attribute that can be divided into sub-parts.
Explanation:A Composite Attribute can be divided into smaller sub-parts with independent meanings (e.g., Address can be divided into Street, City, Zip Code).
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36A Candidate Key is:
A.A super key with no proper subset that is also a super key.
B.Any key that allows null values.
C.A key that connects two tables.
D.A key automatically generated by the DBMS.
Correct Answer: A super key with no proper subset that is also a super key.
Explanation:A Candidate Key is a minimal super key. If any attribute is removed from it, it no longer uniquely identifies the tuple.
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37The CAP Theorem in the context of Non-Relational databases stands for:
Explanation:The CAP theorem states that a distributed data store can effectively provide only two of the following three guarantees: Consistency, Availability, and Partition Tolerance.
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38Which of the following represents the relationship between Schema and Instance?
A.Schema changes often; Instance is static.
B.Schema is the variable; Instance is the type.
C.Schema is the structure (Type); Instance is the data (Variable).
D.They are the same thing.
Correct Answer: Schema is the structure (Type); Instance is the data (Variable).
Explanation:The Schema corresponds to the variable declaration (type definition) in programming, while the Instance corresponds to the value of the variable at a specific time.
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39In an ER diagram, a Weak Entity Set is represented by:
A.A double rectangle.
B.A dashed rectangle.
C.A double diamond.
D.A rectangle with rounded corners.
Correct Answer: A double rectangle.
Explanation:A Weak Entity Set is depicted by a double rectangle (a rectangle inside another rectangle).
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40Which type of data independence is generally harder to achieve?
A.Physical Data Independence
B.Logical Data Independence
C.Both are equally hard
D.Neither is difficult
Correct Answer: Logical Data Independence
Explanation:Logical Data Independence is harder to achieve because application programs are heavily dependent on the logical structure of the data they access.
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41In the relational model, the value NULL represents:
A.Zero
B.Empty String
C.Unknown or Inapplicable value
D.An error
Correct Answer: Unknown or Inapplicable value
Explanation:NULL signifies that the value is either unknown (it exists but we don't know it) or inapplicable (the attribute does not apply to this tuple).
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42Which of the following is an advantage of DBMS over file systems regarding security?
A.DBMS allows concurrent access.
B.DBMS enforces data types.
C.DBMS can restrict access to specific data views for specific users.
D.DBMS uses more disk space.
Correct Answer: DBMS can restrict access to specific data views for specific users.
Explanation:DBMS provides robust security mechanisms, allowing administrators to define granular access rights (authorization) so users only see what they are allowed to see.
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43What is the primary function of the Data Dictionary?
A.To store the actual data of the users.
B.To store metadata about the database structure.
C.To compile SQL queries.
D.To manage buffer memory.
Correct Answer: To store metadata about the database structure.
Explanation:The Data Dictionary (or System Catalog) stores metadata, which includes schema definitions, user information, constraints, and other structural data.
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44A relationship where one entity from set A is associated with at most one entity in set B, and vice versa, is called:
A.One-to-Many
B.Many-to-One
C.One-to-One
D.Many-to-Many
Correct Answer: One-to-One
Explanation:This describes a One-to-One () relationship cardinality.
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45In a Relational Schema, if an attribute is a Foreign Key, it must match a value in the ____ of the referenced relation.
A.Any attribute
B.Foreign Key
C.Primary Key (or Candidate Key)
D.Composite attribute
Correct Answer: Primary Key (or Candidate Key)
Explanation:Referential integrity requires that a Foreign Key value must refer to an existing Primary Key (or unique Candidate Key) value in the referenced table (or be NULL).
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46Which model is considered a Schema-less model?
A.Relational Model
B.Network Model
C.NoSQL (e.g., Document Model)
D.Hierarchical Model
Correct Answer: NoSQL (e.g., Document Model)
Explanation:NoSQL databases (like Document stores) are often described as schema-less or having a flexible schema, allowing different documents in the same collection to have different fields.
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47The Data Abstraction level that describes what data is stored and the relationships is:
A.Physical Level
B.Logical Level
C.View Level
D.Network Level
Correct Answer: Logical Level
Explanation:The Logical Level abstracts away the physical storage details and focuses on the data types, fields, and relationships.
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48In an ER Diagram, attributes are connected to entity sets by:
A.Dashed lines
B.Double lines
C.Straight lines
D.Arrows
Correct Answer: Straight lines
Explanation:Standard ER notation uses simple straight lines to connect attributes to their respective entity sets.
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49Which of the following is a disadvantage of a DBMS?
A.Improved Data Integrity
B.Data Independence
C.High cost of hardware and software
D.Reduced Data Redundancy
Correct Answer: High cost of hardware and software
Explanation:Implementing a DBMS can be expensive due to the cost of the software (e.g., Oracle), the robust hardware required to run it, and the specialized personnel (DBAs) needed to manage it.
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50If a relationship set connects Entity Sets and , and the relationship is Many-to-Many, how is this represented in the Relational Model?
A.Adding a foreign key to Table A.
B.Adding a foreign key to Table B.
C.Creating a new table consisting of primary keys from both A and B.
D.Merging Table A and Table B.
Correct Answer: Creating a new table consisting of primary keys from both A and B.
Explanation:A Many-to-Many relationship requires a separate junction (or join) table containing the Primary Keys of both participating entities to serve as Foreign Keys.