IT - Databases

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Author:
Camskie
ID:
308204
Filename:
IT - Databases
Updated:
2015-09-20 22:07:52
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IT
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Ken's Group
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  1. Individual, unrelated files.
    Flat Files
  2. Collection of related data.
    Database
  3. Advantages of databases:
    • Less redundancy
    • Inconsistency avoidance
    • Efficiency
    • Data integrity
    • Confidentiality
  4. Defines, creates and maintains a database.
    DATABASE MANAGEMENT SYSTEMS (DBMS)
  5. A DBMS is a combination of five components:
    • Hardware
    • Software
    • Data Users 
    • Procedures
  6. Two (2) categories of data users:
    • End Users
    • Application Programs
  7. The American National Standards Institute/Standards Planning and Requirements Committee (ANSI/SPARC) has established three-level architecture for a DBMS:
    • Internal level
    • Conceptual level 
    • External level
  8. Determines where data is actually stored on the storage devices.
    Internal Level
  9. Defines the logical view of the data.
    Conceptual Level
  10. Interacts directly with the user (end users or application programs).
    External Level
  11. > defines the logical design of data.
    > also describes the relationships between different parts of the data.
    Database Model
  12. 3 database models used:
    • Hierarchical database model
    • Network database model
    • Relational database model
  13. Data is organized as an inverted tree. Each entity has only one parent but can have several children.
    Hierarchical database model
  14. At the top of the hierarchy, there is one entity, which is called the ____.
    root
  15. The entities are organized in a graph, in which some entities can be accessed through several paths.
    Network database model
  16. Data is organized in two-dimensional tables called relations. The tables or relations are, however, related to each other
    Relational database model
  17. 2-dimensional tables are called ____.
    Relations
  18. The data is represented as a set of relations.
    Relational Database Management System (RDBMS)
  19. A relation in an RDBMS has the following FEATURES:
    • Name
    • Attributes
    • Tuples
  20. A name that is unique among other relations.
    Name
  21. Each column in a relation is called an ______.
    Attribute
  22. Each row in a relation is called a ____.
    Tuple
  23. 9 OPERATIONS ON RELATIONS
    • Insert Operation
    • Delete Operation
    • Update Operation
    • Select Operation
    • Project Operation
    • Join Operation
    • Union Operation
    • Intersection Operation
    • Difference Operation
  24. Instead of discussing these operations in the abstract, we describe each operation as defined in the database query language _____________.
    SQL (Structured Query Language)
  25. > is the language standardized by the American National Standards Institute (ANSI) and the International Organization for Standardization (ISO) for use on relational databases.
    > it is a declarative rather than procedural language, which means that users declare what they want without having to write a step-by-step procedure.
    Structured Query Language (SQL)
  26. Uses several geometric shapes.
    • Rectangles
    • Ellipses
    • Diamonds
    • Lines link
  27. Represent entity sets.
    Rectangles
  28. Represent attributes.
    Ellipses
  29. Represent relationship sets.
    Diamonds
  30. Attributes to entity sets and link entity sets to relationships sets.
    Lines link
  31. Is the process by which a given set of relations are transformed to a new set of relations with a more solid structure.
    Normalization
  32. Two other common models:
    • Distributed Databases
    • Object-oriented Databases
  33. Is not a new model, but is based on the relational model. However, the data is stored on several computers that communicate through the Internet or a private wide area network.
    Distributed Databases
  34. Tries to keep the advantages of the relational model and at the same time allows applications to access structured data.
    Object-oriented Databases

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