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Questions and Answers

In a 2-Tier Architecture, where are the user interfaces and application programs run?

  • On the server-side
  • On the client-side (correct)
  • On both the client-side and server-side
  • On a third separate layer

    • What is the main responsibility of the server-side in a 2-Tier Architecture?

  • To provide functionalities like query processing and transaction management (correct)
  • To interact with the user
  • To run application programs
  • To establish a connection with the client-side

    • What is the purpose of the additional layer in a 3-Tier Architecture?

  • To provide an additional layer of security
  • To act as an intermediary between the client and server (correct)
  • To reduce the load on the client-side
  • To enable direct communication between the client and server

    • What is the benefit of using a 3-Tier Architecture in large web applications?

    <p>It allows for abstraction and scalability</p> Signup and view all the answers

    What is the primary function of a data model in a DBMS?

    <p>To define the logical structure of a database</p> Signup and view all the answers

    What is the Entity-Relationship (ER) Model based on?

    <p>Entities, relationships, and attributes</p> Signup and view all the answers

    What is the main advantage of using an ER Model in database design?

    <p>It is best used for the conceptual design of a database</p> Signup and view all the answers

    What is the purpose of an ER Model in a DBMS?

    <p>To introduce abstraction in a DBMS</p> Signup and view all the answers

    What does a database schema define?

    <p>How the data is organized and the relationships among them</p> Signup and view all the answers

    What is the main purpose of a database schema?

    <p>To help programmers understand the database</p> Signup and view all the answers

    What are the two categories of a database schema?

    <p>Physical and Logical Database Schema</p> Signup and view all the answers

    What is a physical database schema?

    <p>It defines the actual storage of data and its form of storage</p> Signup and view all the answers

    What is a database instance?

    <p>A state of operational database with data at any given time</p> Signup and view all the answers

    What does a database instance contain?

    <p>A snapshot of the database</p> Signup and view all the answers

    What does a DBMS ensure?

    <p>That every instance of the database is in a valid state</p> Signup and view all the answers

    What is data independence?

    <p>The ability of a database system to contain a lot of data in addition to users’ data</p> Signup and view all the answers

    What is the name of the database management system based on the relational model introduced by E.F. Codd?

    <p>RDBMS</p> Signup and view all the answers

    Who introduced the relational model of database systems?

    <p>E.F. Codd</p> Signup and view all the answers

    What is the number of rules introduced by E.F. Codd for a relational database?

    <p>12</p> Signup and view all the answers

    According to Rule 1, where must everything in a database be stored?

    <p>In a table format</p> Signup and view all the answers

    What is guaranteed by Rule 2 of E.F. Codd's rules?

    <p>Logical access to data</p> Signup and view all the answers

    What is the purpose of Rule 3 of E.F. Codd's rules?

    <p>To handle NULL values</p> Signup and view all the answers

    What is the name of the online catalog that stores the structure description of the entire database?

    <p>Data dictionary</p> Signup and view all the answers

    What is the characteristic of the language that can be used to access the database according to Rule 5?

    <p>Linear syntax</p> Signup and view all the answers

    What is the main purpose of the Non-Subversion Rule in a database system?

    <p>To prevent the interface from bypassing security and integrity constraints</p> Signup and view all the answers

    How is data represented in a Relational Database Management System (RDBMS)?

    <p>In terms of tuples (rows)</p> Signup and view all the answers

    What is the primary function of a table in an RDBMS?

    <p>To store data in a structured format</p> Signup and view all the answers

    What is a field in a table?

    <p>A smaller entity of the table which contains specific information about every record</p> Signup and view all the answers

    What is a row in a table?

    <p>A specific information of each individual entry in the table</p> Signup and view all the answers

    What is a column in a table?

    <p>A vertical entity in the table which contains all information associated with a specific field</p> Signup and view all the answers

    What does a NULL value in a table specify?

    <p>The field has been left blank during record creation</p> Signup and view all the answers

    What is the primary key in a table?

    <p>A unique identifier for each record in the table</p> Signup and view all the answers

    What is normalization in database management?

    <p>A mathematically rich and scientific process that reduces data redundancy</p> Signup and view all the answers

    What is the primary goal of consistency in a database?

    <p>To maintain a consistent state in every relation of a database</p> Signup and view all the answers

    What is the main advantage of query language in DBMS?

    <p>It makes it more efficient to retrieve and manipulate data</p> Signup and view all the answers

    What does ACID stand for in DBMS?

    <p>Atomicity, Consistency, Isolation, Durability</p> Signup and view all the answers

    What is an advantage of multi-user and concurrent access in DBMS?

    <p>It enables multiple users to access and manipulate data in parallel</p> Signup and view all the answers

    What is the purpose of multiple views in DBMS?

    <p>To provide a concentrated view of the database according to user requirements</p> Signup and view all the answers

    What is a characteristic of DBMS that is not present in file-processing systems?

    <p>Query language</p> Signup and view all the answers

    Why are ACID properties important in DBMS?

    <p>They help the database stay healthy in multi-transactional environments and in case of failure</p> Signup and view all the answers

    What is an entity in an ER Model?

    <p>A real-world entity having properties called attributes</p> Signup and view all the answers

    What is the purpose of a database schema?

    <p>To define the logical view of the entire database</p> Signup and view all the answers

    What is a characteristic of normalized relations in the Relational Model?

    <p>Values saved are atomic</p> Signup and view all the answers

    What is the function of mapping cardinalities in ER Model?

    <p>To define the relationships among entities</p> Signup and view all the answers

    What is a characteristic of a relational model?

    <p>Data is stored in tables called relations</p> Signup and view all the answers

    What is the primary function of a table in a Relational Database Management System (RDBMS)?

    <p>To store data in a tabular structure</p> Signup and view all the answers

    What does a NULL value in a table specify?

    <p>A missing or unknown value</p> Signup and view all the answers

    What is the primary goal of consistency in a database?

    <p>To ensure data accuracy and integrity</p> Signup and view all the answers

    What is the primary function of a table in an RDBMS?

    <p>To store a collection of related data entries</p> Signup and view all the answers

    What does a NULL value in a table specify?

    <p>That the field has been left blank during record creation</p> Signup and view all the answers

    What is the main purpose of Rule 12: Non-Subversion Rule in a database system?

    <p>To prevent subversion of the system and bypass security and integrity constraints</p> Signup and view all the answers

    How is data represented in a Relational Database Management System (RDBMS)?

    <p>In terms of tuples (rows)</p> Signup and view all the answers

    What is the primary function of a field in a table?

    <p>To contain specific information about every record in the table</p> Signup and view all the answers

    What is a column in a table?

    <p>A vertical entity in the table</p> Signup and view all the answers

    What is a row in a table?

    <p>A collection of specific information of each individual entry in the table</p> Signup and view all the answers

    Why is data normalization important in a database?

    <p>To remove data redundancy and improve data integrity</p> Signup and view all the answers

    What is entity integrity in a database?

    <p>It specifies that there should be no duplicate rows in a table.</p> Signup and view all the answers

    What is the main difference between DBMS and RDBMS in terms of data storage?

    <p>DBMS stores data in a navigational form, while RDBMS stores data in a tabular form.</p> Signup and view all the answers

    What is referential integrity in a database?

    <p>It ensures that rows cannot be deleted, which are used by other records.</p> Signup and view all the answers

    What is the purpose of normalization in a database?

    <p>To minimize data redundancy and improve data integrity.</p> Signup and view all the answers

    What is the primary function of a table in an RDBMS?

    <p>To store data in a tabular form.</p> Signup and view all the answers

    What is the main advantage of RDBMS over DBMS?

    <p>RDBMS defines the integrity constraint for the purpose of ACID property.</p> Signup and view all the answers

    What is the characteristic of a database that is not present in file-processing systems?

    <p>Multi-user and concurrent access.</p> Signup and view all the answers

    What is the primary goal of consistency in a database?

    <p>To minimize data redundancy and improve data integrity.</p> Signup and view all the answers

    In a 3-Tier Architecture, what is the role of the application server?

    <p>To communicate with the database system</p> Signup and view all the answers

    What is the primary purpose of a data model in a DBMS?

    <p>To define how data is connected to each other and processed</p> Signup and view all the answers

    What is the characteristic of the Entity-Relationship (ER) Model?

    <p>It is based on the notion of real-world scenarios and relationships among them</p> Signup and view all the answers

    What is the benefit of using a 3-Tier Architecture?

    <p>It provides abstraction and hides the complexity of the database from the user</p> Signup and view all the answers

    What is the purpose of data models in a DBMS?

    <p>To introduce abstraction in a DBMS</p> Signup and view all the answers

    What is the main advantage of using an ER Model in database design?

    <p>It is best used for the conceptual design of a database</p> Signup and view all the answers

    What is normalization in database management?

    <p>The process of organizing a database to minimize data redundancy and improve data integrity</p> Signup and view all the answers

    What is the primary goal of consistency in a database?

    <p>To ensure that data is accurate and reliable</p> Signup and view all the answers

    What is the purpose of query language in DBMS?

    <p>To retrieve and manipulate data efficiently</p> Signup and view all the answers

    What is the primary goal of consistency in a database?

    <p>To maintain every relation in a consistent state</p> Signup and view all the answers

    What is normalization in database management?

    <p>A process that reduces data redundancy</p> Signup and view all the answers

    What does ACID stand for in DBMS?

    <p>Atomicity, Consistency, Isolation, Durability</p> Signup and view all the answers

    What is an advantage of multi-user and concurrent access in DBMS?

    <p>Multiple users can access and manipulate data in parallel</p> Signup and view all the answers

    What is the purpose of multiple views in DBMS?

    <p>To provide different views of the database for different users</p> Signup and view all the answers

    What is a characteristic of DBMS that is not present in file-processing systems?

    <p>Query language for retrieving and manipulating data</p> Signup and view all the answers

    What is the benefit of using normalization in database design?

    <p>Reduced data redundancy</p> Signup and view all the answers

    What is the main purpose of multiple views in DBMS?

    <p>To offer security to some extent by limiting access</p> Signup and view all the answers

    What is the primary function of the server-side in a 2-Tier Architecture?

    <p>To provide functionalities like query processing and transaction management</p> Signup and view all the answers

    What is the primary responsibility of Administrators in a DBMS?

    <p>To maintain the DBMS and apply limitations to users</p> Signup and view all the answers

    What is the main benefit of using a DBMS over traditional file systems?

    <p>Enhanced security features</p> Signup and view all the answers

    What is the main advantage of using a 3-Tier Architecture?

    <p>It provides an additional layer of abstraction between the client and server</p> Signup and view all the answers

    What does a data model define in a DBMS?

    <p>How the logical structure of a database is modeled</p> Signup and view all the answers

    What is the primary role of Designers in a DBMS?

    <p>To design the database</p> Signup and view all the answers

    What is the Entity-Relationship (ER) Model based on?

    <p>Real-world entities, relationships, and attributes</p> Signup and view all the answers

    How do DBMS offer security features?

    <p>By offering methods to impose constraints while entering and retrieving data</p> Signup and view all the answers

    What is the main advantage of categorizing DBMS users?

    <p>To restrict access to data based on user roles and departments</p> Signup and view all the answers

    What is the purpose of an ER Model in a DBMS?

    <p>To introduce abstraction in a DBMS</p> Signup and view all the answers

    What is the benefit of using an ER Model in database design?

    <p>It is best used for the conceptual design of a database</p> Signup and view all the answers

    What do Administrators look after in a DBMS?

    <p>DBMS resources like system licenses and required tools</p> Signup and view all the answers

    What does an ER Model create while formulating a real-world scenario into a database model?

    <p>Entities, relationships, and attributes</p> Signup and view all the answers

    What is the benefit of using DBMS over traditional file systems?

    <p>Enhanced security features and data isolation</p> Signup and view all the answers

    What is the main advantage of using a 3-Tier Architecture in large web applications?

    <p>It provides an additional layer of abstraction</p> Signup and view all the answers

    What is the main benefit of normalization in database management?

    <p>Reducing data redundancy</p> Signup and view all the answers

    What is the primary function of a DBMS in terms of consistency?

    <p>Providing greater consistency than file-processing systems</p> Signup and view all the answers

    What is the purpose of query language in a DBMS?

    <p>To retrieve and manipulate data</p> Signup and view all the answers

    What is the primary advantage of ACID properties in a DBMS?

    <p>Ensuring data consistency and durability</p> Signup and view all the answers

    What is the primary benefit of multi-user and concurrent access in a DBMS?

    <p>Allowing multiple users to access and manipulate data in parallel</p> Signup and view all the answers

    What is the primary purpose of multiple views in a DBMS?

    <p>Providing a concentrated view of the database according to user requirements</p> Signup and view all the answers

    What is a characteristic of a DBMS that is not present in file-processing systems?

    <p>Support for multi-user environment</p> Signup and view all the answers

    Why are ACID properties important in a DBMS?

    <p>To ensure data consistency and durability in multi-transactional environments</p> Signup and view all the answers

    What is the primary function of metadata in a database?

    <p>To store data about the database itself</p> Signup and view all the answers

    What is the benefit of logical data independence?

    <p>It allows changes to the schema without affecting the physical storage</p> Signup and view all the answers

    What is the primary function of physical data independence?

    <p>To change the physical storage without affecting the schema</p> Signup and view all the answers

    What is the characteristic of RDBMS?

    <p>It stores data in a relational structure</p> Signup and view all the answers

    What is the advantage of data independence?

    <p>It allows changes to the physical storage without affecting the schema</p> Signup and view all the answers

    What is the purpose of metadata in a database?

    <p>To store data about the database itself</p> Signup and view all the answers

    What is the benefit of data independence in a DBMS?

    <p>It allows changes to the physical storage without affecting the schema</p> Signup and view all the answers

    What is the characteristic of a layered architecture in metadata?

    <p>It allows changes to the schema without affecting the physical storage</p> Signup and view all the answers

    What category of data integrity ensures that there are no duplicate rows in a table?

    <p>Entity integrity</p> Signup and view all the answers

    What is the main difference between DBMS and RDBMS in terms of data storage?

    <p>DBMS stores data as files, while RDBMS stores data in tables</p> Signup and view all the answers

    What is the purpose of normalization in RDBMS?

    <p>To ensure data consistency and reduce data redundancy</p> Signup and view all the answers

    What category of data integrity enforces valid entries for a given column by restricting the type, format, or range of values?

    <p>Domain integrity</p> Signup and view all the answers

    What is the primary function of a primary key in a table?

    <p>To identify a unique row in a table</p> Signup and view all the answers

    What is the purpose of user-defined integrity?

    <p>To define specific business rules defined by users</p> Signup and view all the answers

    What is the main advantage of RDBMS over DBMS?

    <p>RDBMS defines the integrity constraint for ACID property, while DBMS does not</p> Signup and view all the answers

    What is the main difference between DBMS and RDBMS in terms of normalization?

    <p>RDBMS applies normalization, while DBMS does not</p> Signup and view all the answers

    What is the primary benefit of normalization in a database?

    <p>Reducing data redundancy</p> Signup and view all the answers

    What is the main advantage of using a DBMS over file-processing systems?

    <p>All of the above</p> Signup and view all the answers

    What do ACID properties ensure in a DBMS?

    <p>Data consistency and durability</p> Signup and view all the answers

    What is the primary purpose of multiple views in a DBMS?

    <p>Providing a concentrated view of the database for different users</p> Signup and view all the answers

    What is a characteristic of a DBMS that is not present in file-processing systems?

    <p>All of the above</p> Signup and view all the answers

    What is the primary goal of consistency in a database?

    <p>Ensuring every relation remains consistent</p> Signup and view all the answers

    What is the main advantage of query language in a DBMS?

    <p>Enabling efficient data retrieval and manipulation</p> Signup and view all the answers

    What is the advantage of multi-user and concurrent access in a DBMS?

    <p>Enabling multiple users to access and manipulate data in parallel</p> Signup and view all the answers

    What is an entity in an ER Model?

    <p>A real-world entity having properties called attributes</p> Signup and view all the answers

    What is the purpose of mapping cardinalities in ER Model?

    <p>To define the number of associations between two entities</p> Signup and view all the answers

    What is a characteristic of a relational model?

    <p>It is based on first-order predicate logic</p> Signup and view all the answers

    What is stored in tables called relations in the Relational Model?

    <p>Atomic values</p> Signup and view all the answers

    What is a database schema?

    <p>A logical view of the entire database</p> Signup and view all the answers

    What is the function of each column in a relation?

    <p>To store values from the same domain</p> Signup and view all the answers

    What is the main highlight of the Relational Model?

    <p>Data is stored in tables called relations</p> Signup and view all the answers

    What is the characteristic of normalized relations in the Relational Model?

    <p>Values saved are atomic values</p> Signup and view all the answers

    What is the primary function of a database schema?

    <p>To define how the data is organized and the relations among them</p> Signup and view all the answers

    What does a physical database schema pertain to?

    <p>The actual storage of data and its form of storage</p> Signup and view all the answers

    What does a database instance contain?

    <p>A snapshot of the database at any given time</p> Signup and view all the answers

    What is the primary purpose of a database schema?

    <p>To help programmers understand the database</p> Signup and view all the answers

    What is a logical database schema?

    <p>A set of logical constraints that need to be applied on the data</p> Signup and view all the answers

    What is the primary difference between a database schema and a database instance?

    <p>A database schema is the skeleton of the database, while a database instance is a snapshot of the database</p> Signup and view all the answers

    What does a DBMS ensure?

    <p>That its every instance is in a valid state</p> Signup and view all the answers

    Who are the beneficiaries of having a DBMS?

    <p>End users</p> Signup and view all the answers

    What is the purpose of the 1-Tier architecture?

    <p>For development of the local application, where programmers can directly communicate with the database for the quick response</p> Signup and view all the answers

    What is used for interaction in the two-tier architecture?

    <p>API's like: ODBC, JDBC</p> Signup and view all the answers

    What is the basic architecture used to deal with a large number of PCs, web servers, database servers and other components that are connected with networks?

    <p>Client-server architecture</p> Signup and view all the answers

    What are the two main types of database architecture?

    <p>Single tier and multi-tier</p> Signup and view all the answers

    What is the main characteristic of the 2-Tier architecture?

    <p>It has a client-server architecture</p> Signup and view all the answers

    Why is the 1-Tier architecture not suitable for end users?

    <p>Because it doesn't provide a handy tool for end users</p> Signup and view all the answers

    Who designs the whole set of entities, relations, constraints, and views?

    <p>They</p> Signup and view all the answers

    What is the primary goal of Rule 6: View Updating Rule?

    <p>To make all views of a database updatable by the system</p> Signup and view all the answers

    What is the benefit of Rule 8: Physical Data Independence?

    <p>It allows changes in physical structure without impacting applications</p> Signup and view all the answers

    What is the primary goal of Rule 9: Logical Data Independence?

    <p>To enable changes in logical data without impacting applications</p> Signup and view all the answers

    What is the primary benefit of Rule 10: Integrity Independence?

    <p>It enables independent modification of integrity constraints</p> Signup and view all the answers

    What is the primary goal of Rule 11: Distribution Independence?

    <p>To give users the impression that data is located at one site only</p> Signup and view all the answers

    What is the main advantage of Rule 7: High-Level Insert, Update, and Delete Rule?

    <p>It supports high-level insertion, updation, and deletion</p> Signup and view all the answers

    What is the primary goal of Rule 6: View Updating Rule and Rule 7: High-Level Insert, Update, and Delete Rule?

    <p>To make views updatable and enable set operations</p> Signup and view all the answers

    What is the common theme among Rule 8: Physical Data Independence, Rule 9: Logical Data Independence, and Rule 10: Integrity Independence?

    <p>Independence from applications and modifications</p> Signup and view all the answers

    Study Notes

    Database Management Systems (DBMS)

    • A DBMS is a mathematically rich and scientific process that reduces data redundancy.
    • Consistency is a state where every relation in a database remains consistent, and DBMS provides greater consistency than earlier forms of data storing applications.

    Characteristics of DBMS

    • Query Language: DBMS is equipped with a query language that makes it efficient to retrieve and manipulate data.
    • ACID Properties: DBMS follows the concepts of Atomicity, Consistency, Isolation, and Durability (ACID) to ensure the database stays healthy in multi-transactional environments.
    • Multiuser and Concurrent Access: DBMS supports a multi-user environment and allows them to access and manipulate data in parallel.
    • Multiple Views: DBMS offers multiple views for different users, enabling them to have a concentrated view of the database according to their requirements.

    2-Tier Architecture

    • The 2-Tier architecture consists of a client-side and a server-side.
    • The client-side application interacts with the server-side, which provides functionalities like query processing and transaction management.
    • The client-side establishes a connection with the server-side to communicate with the DBMS.

    3-Tier Architecture

    • The 3-Tier architecture contains an additional layer between the client and server.
    • The client-side application interacts with an application server, which communicates with the database system.
    • The end-user has no idea about the existence of the database beyond the application server.
    • The 3-Tier architecture is used in large web applications.

    DBMS Data Models

    • Data models define how the logical structure of a database is modeled.
    • Data models define how data is connected to each other and how they are processed and stored inside the system.

    Entity-Relationship Model

    • The Entity-Relationship (ER) Model is based on the notion of real-world entities and relationships among them.
    • The ER Model creates entity sets, relationship sets, general attributes, and constraints.
    • The ER Model is best used for the conceptual design of a database.

    Database Schema

    • A database schema defines the entities and relationships among them.
    • A database schema contains a descriptive detail of the database, which can be depicted by means of schema diagrams.
    • The database schema can be divided into two categories: Physical Database Schema and Logical Database Schema.

    Database Instance

    • A database instance is a state of an operational database with data at any given time.
    • A database instance contains a snapshot of the database and tends to change with time.
    • A DBMS ensures that every instance (state) is in a valid state, following all the validations, constraints, and conditions imposed by the database designers.

    Data Independence

    • A database system normally contains a lot of data in addition to users' data.
    • The Relational Data Base Management System (RDBMS) is based on the relational model introduced by E.F.Codd.
    • Codd's 12 rules define the requirements for a true relational database.

    Codd's 12 Rules

    • Rule 1: Information Rule - All data is stored in table format.
    • Rule 2: Guaranteed Access Rule - Every data element is accessible logically with a combination of table-name, primary-key, and attribute-name.
    • Rule 3: Systematic Treatment of NULL Values - NULL values are given a systematic and uniform treatment.
    • Rule 4: Active Online Catalog - The structure description of the entire database is stored in an online catalog.
    • Rule 5: Comprehensive Data Sub-Language Rule - A database can only be accessed using a language having linear syntax that supports data definition, data manipulation, and transaction management operations.
    • Rule 12: Non-Subversion Rule - The interface must not be able to subvert the system and bypass security and integrity constraints.

    Relational Database Management System (RDBMS)

    • RDBMS is most commonly used database.
    • It contains a number of tables, and each table has its own primary key.
    • Data is represented in terms of tuples (rows) in RDBMS.
    • A table is a collection of related data entries and contains rows and columns to store data.

    Database Table

    • A table is the simplest example of data storage in RDBMS.
    • A table consists of fields, rows, and columns to store data.

    Field

    • A field is a smaller entity of the table that contains specific information about every record in the table.

    Row/Record

    • A row of a table is also called a record.
    • It contains specific information of each individual entry in the table.

    Column

    • A column is a vertical entity in the table that contains all information associated with a specific field in a table.

    NULL Values

    • The NULL value of the table specifies that the field has been left blank during record creation.
    • It is different from the value filled with zero or a field that contains space.

    Database Management System (DBMS)

    • DBMS is a mathematically rich and scientific process that reduces data redundancy
    • Consistency: a state where every relation in a database remains consistent
    • DBMS provides greater consistency compared to earlier forms of data storing applications like file-processing systems
    • Query Language: DBMS is equipped with a query language, making it efficient to retrieve and manipulate data
    • ACID Properties: DBMS follows Atomicity, Consistency, Isolation, and Durability concepts, ensuring database health in multi-transactional environments and in case of failure

    Multiuser and Concurrent Access

    • DBMS supports a multi-user environment, allowing users to access and manipulate data in parallel
    • Multiple views: DBMS offers different views for different users, enabling them to have a concentrated view of the database according to their requirements

    Entity-Relationship (ER) Model

    • ER Model is based on real-world entities and relationships among them
    • Entities: real-world entities having properties called attributes, with attributes defined by their set of values called domain
    • Relationships: logical associations among entities, mapped with entities in various ways, including one-to-one, one-to-many, many-to-one, and many-to-many

    Relational Model

    • The most popular data model in DBMS, based on first-order predicate logic
    • Data is stored in tables called relations
    • Relations can be normalized, with atomic values saved
    • Each row in a relation contains a unique value
    • Each column in a relation contains values from the same domain

    Database Schema

    • A database schema is the skeleton structure that represents the logical view of the entire database
    • Data Integrity: categories include entity integrity, domain integrity, referential integrity, and user-defined integrity

    DBMS vs RDBMS

    • DBMS applications store data as files, while RDBMS applications store data in a tabular form
    • In DBMS, data is generally stored in a hierarchical or navigational form, whereas in RDBMS, tables have an identifier called a primary key
    • Normalization is present in RDBMS, but not in DBMS
    • RDBMS defines integrity constraints, whereas DBMS does not apply security with regards to data manipulation

    Relational Database Management System (RDBMS)

    • Data is represented in terms of tuples (rows) in RDBMS
    • Relational database is most commonly used and contains a collection of organized tables
    • Each table has its own primary key, enabling easy data access

    Database Table

    • A table is a collection of related data entries and contains rows and columns to store data
    • Field: a smaller entity of the table, containing specific information about every record
    • Row/Record: a horizontal entity in the table, containing specific information of each individual entry
    • Column: a vertical entity in the table, containing all information associated with a specific field
    • NULL Values: specify that the field has been left blank during record creation

    2-Tier and 3-Tier Architecture

    • 2-Tier Architecture: client-side application establishes a connection with the server-side DBMS
    • 3-Tier Architecture: contains an application server between the client and server, enabling the client to interact with the application server, which communicates with the database system

    Database Management System (DBMS)

    • DBMS is a mathematically rich and scientific process that reduces data redundancy.

    Characteristics of DBMS

    • Consistency: ensures every relation in a database remains consistent, detecting attempts to leave the database in an inconsistent state.
    • Query Language: allows efficient data retrieval and manipulation through the use of filtering options.
    • ACID Properties:
    • Atomicity: ensures transactions are treated as a single, indivisible unit.
    • Consistency: ensures the database remains in a consistent state after a transaction.
    • Isolation: ensures transactions do not interfere with each other.
    • Durability: ensures transactions are permanently stored in the database.
    • Multiuser and Concurrent Access: supports multiple users accessing and manipulating data simultaneously.
    • Multiple Views: offers different views of the database for different users, allowing them to focus on specific data according to their requirements.
    • Security: imposes constraints on data entry and retrieval, offering multiple levels of security features.

    DBMS Users

    • Administrators: maintain the DBMS, create access profiles for users, and apply limitations to maintain isolation and force security.
    • Designers: design the database, determining what data should be stored and in what format.

    2-Tier and 3-Tier Architecture

    • 2-Tier Architecture:
    • Client-side application interacts directly with the server-side DBMS.
    • Server-side provides query processing and transaction management functionalities.
    • 3-Tier Architecture:
    • Client-side application interacts with an application server, which communicates with the DBMS.
    • End users have no knowledge of the database beyond the application server.
    • Database has no knowledge of users beyond the application server.

    DBMS Data Models

    • Data models define the logical structure of a database.
    • Entity-Relationship (ER) Model:
    • Based on real-world entities and relationships among them.
    • Creates entity sets, relationship sets, general attributes, and constraints.
    • Best used for conceptual database design.
    • ER Model is based on entities, their attributes, and relationships among entities.

    Data Independence

    • Logical Data Independence: ensures changes to table formats do not affect data residing on the disk.
    • Physical Data Independence: allows changing the physical data storage system without impacting the schema or logical data.

    RDBMS

    • RDBMS (Relational Database Management Systems) is based on the relational model.
    • Examples of RDBMS include SQL, MS SQL Server, IBM DB2, ORACLE, My-SQL, and Microsoft Access.
    • Data Integrity in RDBMS:
    • Entity integrity: no duplicate rows in a table.
    • Domain integrity: enforces valid entries for a given column.
    • Referential integrity: rows cannot be deleted that are used by other records.
    • User-defined integrity: enforces specific business rules defined by users.

    DBMS vs RDBMS

    • DBMS stores data in files, while RDBMS stores data in a tabular form.
    • DBMS does not use normalization, while RDBMS uses normalization.
    • DBMS does not apply security constraints, while RDBMS defines integrity constraints for the purpose of ACID properties.

    DBMS Characteristics

    • Consistency: a state where every relation in a database remains consistent, with methods to detect and prevent inconsistent states
    • Query Language: DBMS provides a query language for efficient data retrieval and manipulation, with filtering options to retrieve specific data sets
    • ACID Properties:
      • Atomicity: ensures that database transactions are treated as a single, indivisible unit
      • Consistency: ensures that the database remains in a consistent state, even in the event of a failure
      • Isolation: ensures that concurrent transactions do not interfere with each other
      • Durability: ensures that once a transaction is committed, its effects are permanent
    • Multiuser and Concurrent Access: DBMS supports multiple users accessing and manipulating data in parallel, with restrictions on transactions when users attempt to handle the same data item
    • Multiple Views: DBMS offers multiple views for different users, allowing them to have a concentrated view of the database according to their requirements
    • End Users: individuals who reap the benefits of having a DBMS, ranging from simple viewers to sophisticated users such as business analysts

    DBMS Architecture

    • Client/Server Architecture: a basic architecture used to deal with a large number of PCs, web servers, and database servers connected via networks
    • 1-Tier Architecture:
      • Directly accessible by the user
      • Changes are directly made on the database
      • Not suitable for end-users, but useful for development of local applications
    • 2-Tier Architecture:
      • Basic client-server architecture
      • Applications on the client end communicate directly with the database at the server side using APIs like ODBC and JDBC

    Data Models

    • ER Model:
      • Entities: real-world objects with properties (attributes) and domains
      • Relationships: logical associations among entities, with mapping cardinalities (one-to-one, one-to-many, many-to-one, many-to-many)
    • Relational Model:
      • Data is stored in tables (relations)
      • Relations can be normalized
      • Values saved are atomic values
      • Each row in a relation contains a unique value
      • Each column in a relation contains values from a same domain

    Database Schema

    • Definition: the skeletal structure that represents the logical view of the entire database
    • Components:
      • Entities and relationships among them
      • Constraints that are to be applied on the data
    • Types:
      • Physical Database Schema: pertains to actual storage of data and its form of storage
      • Logical Database Schema: defines logical constraints that need to be applied on the data stored

    Database Instance

    • Definition: a state of an operational database with data at any given time
    • Characteristics:
      • Contains a snapshot of the database
      • Changes with time
      • DBMS ensures that every instance is in a valid state, following all validations, constraints, and conditions imposed by the database designers

    Data Independence

    • Rule 6: View Updating Rule - all views of a database that can theoretically be updated must also be updatable by the system
    • Rule 7: High-Level Insert, Update, and Delete Rule - database must support high-level insertion, updation, and deletion
    • Rule 8: Physical Data Independence - data stored in a database must be independent of the applications that access the database
    • Rule 9: Logical Data Independence - logical data in a database must be independent of its user's view (application)
    • Rule 10: Integrity Independence - database must be independent of the application that uses it, with integrity constraints that can be independently modified
    • Rule 11: Distribution Independence - end-user must not be able to see that the data is distributed over various locations

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    ch3.pdf

    Description

    Learn about normalization, a process that reduces data redundancy, and consistency, a state where every relation in a database remains consistent, in DBMS.

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