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DBMS Overview and Functions
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DBMS Overview and Functions

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@ExaltedOrangutan

Questions and Answers

What does a primary key in a database ensure?

  • Values cannot change
  • Values must be unique (correct)
  • Values can be empty
  • Values may repeat across records

    • A foreign key can establish relationships between tables and may contain NULL values.

    True

    What is an instance in the context of a database?

    A snapshot of the database at a given time.

    A schema describes the overall ______ of the database.

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

    Match the following types of schema with their descriptions:

    <p>Logical Schema = Describes the database at a logical level. Physical Schema = Describes how data is stored physically. View Schema = Defines the design of the database from the view perspective.</p> Signup and view all the answers

    Which of the following characteristics does not apply to primary keys?

    <p>Can contain NULL values</p> Signup and view all the answers

    CRUD operations can modify the instances of a database.

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

    List one key characteristic of a foreign key.

    <p>Referential Integrity.</p> Signup and view all the answers

    What is the main purpose of a Database Management System (DBMS)?

    <p>To manipulate and share databases</p> Signup and view all the answers

    In 1-Tier Architecture, the client and database are located on different machines.

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

    What are the two types of database models mentioned?

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

    APIs such as _____ and _____ are used for client-server communication in 2-Tier Architecture.

    <p>ODBC, JDBC</p> Signup and view all the answers

    Which architecture uses a direct database connection by the client application?

    <p>2-Tier Architecture</p> Signup and view all the answers

    DBMS allows users to retrieve and manipulate data through queries.

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

    Match the following types of DBMS architecture with their descriptions:

    <p>1-Tier = Client, server, and database are all on the same machine 2-Tier = Client communicates directly with the database on the server Client-Server = An architecture where applications run on both client and server</p> Signup and view all the answers

    What is a transaction in the context of a DBMS?

    <p>A transaction refers to a series of operations that may involve reading or writing data in the database.</p> Signup and view all the answers

    Which of the following is NOT a characteristic of a candidate key?

    <p>Foreign key</p> Signup and view all the answers

    A candidate key can contain NULL values.

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

    What are the two categories of database schema?

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

    The __________ table is linked to both the candidates table and the voters table through the IDNUMBER column.

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

    Match the following types of database schema with their descriptions:

    <p>Physical Database Schema = Actual methods of storing data Logical Database Schema = Logical restrictions on stored data</p> Signup and view all the answers

    What does the logical database schema define?

    <p>Tables, views, and integrity constraints</p> Signup and view all the answers

    The candidatesarchive table is used to store current data about candidates.

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

    What is the purpose of a database schema?

    <p>To facilitate programmers' understanding and usage of the database.</p> Signup and view all the answers

    What type of architecture includes an intermediate layer between the client and the server?

    <p>3-Tier Architecture</p> Signup and view all the answers

    In the hierarchical data model, a node can have multiple parents.

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

    Who developed the relational data model and in what year?

    <p>E.F Codd, 1970</p> Signup and view all the answers

    The topmost node in a hierarchical data model is called the ______.

    <p>root node</p> Signup and view all the answers

    Match the following data models with their characteristics:

    <p>Hierarchical Data Model = Organizes data in a tree-like structure Network Data Model = Uses directed graphs and allows multiple parents Relational Data Model = Presents data in the form of tables 3-Tier Architecture = Includes an application server between client and server</p> Signup and view all the answers

    Which data model was developed in 1968 and is considered the oldest?

    <p>Hierarchical Data Model</p> Signup and view all the answers

    The network data model organizes data in a tree structure.

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

    What is one key feature of the relational data model in terms of data presentation?

    <p>Data is presented in the form of tables.</p> Signup and view all the answers

    Study Notes

    DATABASE MANAGEMENT SYSTEM (DBMS)

    • A DBMS is software that assists in creating and maintaining databases.
    • It allows users to define, manipulate, and share data effectively across various applications.

    HOW DBMS WORKS

    • Application programs interact with the database by sending queries to the DBMS.
    • Queries trigger transactions that may read data from or write data into the database.

    DATABASE

    • Databases are designed to store critical information, allowing quick and secure data access.

    DBMS ARCHITECTURE

    • Database architecture is chosen based on factors like database size, number of users, and user relationships.

    TYPES OF DBMS ARCHITECTURE

    • 1-Tier Architecture:

      • Users access the database directly on the same machine where the DBMS operates.

    • 2-Tier Architecture:

      • Utilizes a client-server model where the client application communicates directly with the database server.
      • APIs like ODBC and JDBC facilitate this interaction.
      • Offers easier maintenance but can underperform with high user loads.

    • 3-Tier Architecture:

      • Includes an intermediary application server between the client and the database server.
      • The client communicates with the application server, which processes queries and data management.

    DATA MODELS

    • Hierarchical Data Model:

      • Introduced by IBM in 1968, organized in a tree-like structure with a single parent per node.

    • Network Data Model:

      • An advanced model using directed graphs allowing child nodes to have multiple parents, utilizing records and sets.

    • Relational Data Model:

      • Developed by E.F. Codd in 1970, represents data in tables without physical links, emphasizing ease of query handling.

    SCHEMAS AND INSTANCES

    • Instances:

      • Represent the current state of the database, which can be altered by CRUD operations, but queries do not change instances.

    • Schema:

      • Overall description of database structure, defining how data is stored.

    • Types of Schema:

      • Logical Schema: Designs at a logical level.
      • Physical Schema: Designs at the physical storage level.
      • View Schema: Defines the design at the user view level.

    KEYS IN DATABASE

    • Primary Key:

      • Unique identifier for a table record, must be unique and not null.

    • Foreign Key:

      • Column in one table that creates a link to the primary key in another table, maintaining referential integrity.

    • Candidate Key:

      • A column or set of columns that can uniquely identify a record, must be unique and non-null.

    DATABASE SCHEMA CATEGORIES

    • Physical Database Schema:

      • Explains data storage methods, detailing structures like files and indices.

    • Logical Database Schema:

      • Outlines logical constraints for the data, providing definitions for tables and integrity rules.

    RELATIONSHIPS

    • Relationships between tables ensure data integrity and connectivity. For example, the ballots table relates to the candidates and voters tables via IDNUMBER.

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    Description

    This quiz reviews key concepts of Database Management Systems (DBMS), including their functions and operations. It covers the essential elements that enable users to create, manipulate, and maintain databases. Test your understanding of how DBMS works and its significance in data management.

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