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Summary Principles of Database Management

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  • 1 1. Fundamental Concepts of Database Management

  • File versus Database Approach to Data Management?
    FILE
    - duplicate and redundant info
    - danger inconsistency
    - strong coupling between applications and data
    - hard to manage concurrency
    - hard to integrate applications aimed at cross company services

    DATABASE   
    - more efficient, consistent, easier maintenance
    - loose coupling between application and data
    - facilities for data quierying and retrieval (SQL)
  • What is database model and instance?
    The model provides a description of the database data at different levels of detail and specifies items, characteristics, relationships, constraints, storage details, etc. Specified during database design

    Example:
    Student(number, name, email)
    Course(number, name)
    Building(number, address)

    State represents the data in the database at particular moment. Also called the current set of instance
  • What is a data model? 4 versions
    Provides a clear and unambiguous description of the data items, their relationships and various data constraints from a particular perspective. 

    Conceptual: provides high-level description of the data items with their characteristics and relationships. (EER and object oriented)

    Logical: is a translation or mapping of the conceptual towards a specific implementation environment: CODASYL, relational, object oriented, XML or NoSQL.     

    Internal: represents the data's physical storage details
    External: also called views, tailored towards the needs of specific applications or groups. Subsets of data.
  • Explain the three layer architecture
    External layer with views
    -> External/logical mapping = logical data indepence
    Conceptual/logical layer with data items
    -> logical/internal mapping = physical data independence
    Internal layer: files, disk, cloud
  • Who are the database users?
    1. Information architect: designs conceptual model
    2. Database designer: translate conceptual into logical and internal
    3. Database administrator: responsible for implementation and monitoring  
    4. Application developer: develops database applications
    5. Business user, will run these applications
  • What type of database languages?
    Data definition language (DDL), to express database external, logical and internal models. 

    Data manipulation language (DML), to retrieve, insert, delete and modify data

    Structured Query Language (SQL), offers DDL and DML statements for relational database systems
  • What are the advantages of database systems and management?
    Data independence
    Database modeling
    Managing data
    Managing redundancy
    Integrity rules
    Concurrency
    Backup and recovery facilities
    Data security
    Performance utilities
  • Types of structured data?
    Structured
    - can be described by formal logical data model
    - express integrity rules and enforce correctness of data
    - facilitates searching, processing and analyzing   

    Unstructured
    - no finer grained components that can be interpreted

    Semi structed
    - data which has structure, but irregular and volatile
  • What are the three KPIs of a DBMS?
    - response time denoting the time elapsed between issuing a request and the termination
    - throughput rate representing the transactions per unit of time
    - space utilization referring to the space utilized to store both raw and metadata
  • 2 2. Architecture and Classification

  • Parts in architecture of a dbms?
    Connection and security manager
    DDL compiler
    Query processor
    Storage manager
    DBMS utilities
    DBMS interfaces
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