Monday 26 September 2011

External View Level

The external view level is closest to the users. It is concerned with the way the data is viewed by individual users. You can say that external level is the individual user level. A user can either be an application programmer or an end-user, but DBA is an important special case.
The external level consist of many different external views of database. Each external view describes that a particular user group is interested in and hides the rest of the database from that user group. In addition, different views may have different representations of the same data. For example, one user may view date in the form (day, month, year).. while another may view date as (year, month, day). Some users may view calculated data, which is not actually stored in database. The calculated data is created temporarily when needed. For example, marks of subject "C++" of students are stored in the database and average marks of this subject are calculated by system  when the user refers to it. Similarly, if a date-of-birth of a student is stored in the database then you can find the age of the student.
The external views are defined by means of external schemes, which are written in the data definition language (DDL). Usually, the DBA writes an external schema to create a user view. Each user's view. An external record is a record seen by a particular user (a part of his external view). Actually, an external view is a collection of external records.
The external schemes are compiled by the DBMS and store in its data dictionary. The DBMS uses the external schema created for a specific user, to create a user interface to access the database. Thus user-interface created through external schema accepts and displays information in the format the user expects. It also acts as barrier to hide the information of database from the user that are not permitted to him.

30 comments:

  1. Useful stuff. Write more. Visit my blog similar to this. http://exploredatabase.blogspot.in/

    ReplyDelete
  2. The knowledge of technology you have been sharing thorough this post is very much helpful to develop new idea. here by i also want to share this.
    apple service center chennai | Mac service center in chennai | ipod service center in chennai | Apple laptop service center in chennai

    ReplyDelete
  3. This is really a very good article. Thanks for taking the time to discuss with us, I feel happy about learning this topic. keep sharing your information regularly for my future reference.
    Offshore Software Development Company

    ReplyDelete
  4. Nice Blog Quickbooks is the one of the best accounting software. We are providing technical support in Quickbooks Support Phone Number 1800 -986-4607. if you are facing any trouble in Quickbooks dial our Toll free number +1-800-986-4607 for quick response. Our executive is available 24*7.

    ReplyDelete
  5. Nice Blog ! Looking for support to resolve your issues with QuickBooks Mac? Don't be afraid! We're here to provide you with the best solutions.You just have to call our QuickBooks for Mac Support Phone Number 1-800-986-4607.

    ReplyDelete
  6. Realme Mobile Service center in Chennai
    Realme Servicing by No. 1 Leaders Awesome Services On-time, Every time!
    Realme Mobile Service Center in Chennai

    ReplyDelete
  7. iPhone Service center in Bangalore No. 1 Leaders Awesome Services On-time, Every time!
    iPhone Service Center in Bangalore
    Apple Service center in Bangalore
    Apple Service Center in Bangalore

    ReplyDelete
  8. Mi Service Center in Chennai

    Mi Service Center in Chennai No. 1 Leaders Awesome Services On-time, Every time!
    Mi Service Center in Chennai
    Redmi Service Center in Chennai
    Mi Service Center in Chennai

    ReplyDelete
  9. This comment has been removed by the author.

    ReplyDelete
  10. OnePlus Service Center in Chennai

    OnePlus Service Center in Chennai No. 1 Smart Service On Time, Every Time
    OnePlus Service Center in Chennai
    OnePlus Service Center in Chennai
    OnePlus Service Center in Chennai

    ReplyDelete
  11. Moto service center in Chennai
    Leading Motorola Service Center In Chennai. Fast & Reliable Services On-time, Every time!
    Moto service center in Chennai
    Motorola Service Center In Chennai
    Motorola Service Center In Chennai

    ReplyDelete
  12. Iphone service center in Chennai

    Iphone service Center in Chennai offers you best quality of Services On-time, Every time!
    IPhone Service Center in Chennai
    Apple Iphone Service center in Chennai
    Apple Service Center in Chennai
    Apple Service center in Chennai
    IPhone Service Center in Chennai

    ReplyDelete
  13. LG Mobile Service Center In Chennai
    LG Mobile Service Center In Chennai. Providing Fast, Honest, Reliable & Cost Effective Service Solutions to The LG Mobile Users.
    LG Mobile Service Center In Chennai

    ReplyDelete
  14. Sony Mobile Service Center In Chennai
    Sony Servicing by No. 1 Leaders Awesome Services On-time, Every time!
    Sony Mobile Service Center In Chennai

    ReplyDelete
  15. Nokia Mobile Service Center In Chennai
    Nokia Mobile Service Center In Chennai. Providing Fast, Honest, Reliable & Cost Effective Service Solutions to The Nokia Mobile Users.
    NOkia Mobile Service Center In Chennai

    ReplyDelete
  16. Honor service center in Chennai

    Honor Service Center in Chennai for the Best & Right Place to service your Honor mobile phone.
    Honor Service Center in Chennai

    ReplyDelete
  17. OPPO Service Center In Chennai
    OPPO Service Center Chennai is an end-to-end OPPO service and repair solutions Center.
    OPPO Service Center In Chennai

    ReplyDelete
  18. Apple Imacbook Service Center in Chennai

    Apple Laptop Service Center in Chennai offers you best quality of Services On-time, Every time!
    Apple Laptop Service Center in Chennai

    ReplyDelete
  19. Acer Service Center in Chennai

    Acer Service Center in Chennai Best service for all model acer laptop and desktop Services On-time, Every time!
    Acer Laptop Service Center in Chennai
    Acer Service Center in Chennai
    Acer Service Center in Chennai

    ReplyDelete
  20. Awesome Post!!!


    Redmi Service Center in Chennai

    Redmi Service Center in Chennai No. 1 Leaders Awesome Services On-time, Every time!
    Redmi Service center in chennai
    Mi Service Center in Chennai
    Mi Service Center in Chennai

    ReplyDelete
  21. WOW Great Post!!!

    Apple iPhone Service Center in Chennai

    Chennai No-1 Apple iPhone Service Center in Chennai
    Apple iPhone Service Center in Chennai
    Iphone Service Center in Chennai
    Iphone Service Center in Chennai
    Apple Service Center In Chennai
    Apple Service Center In Chennai

    ReplyDelete
  22. This comment has been removed by the author.

    ReplyDelete
  23. WOW Great Post!!!

    Nokia Service Center In Chennai

    Nokia service center in Chennai offers you a secure and trusted service for all types of mobiles
    Nokia Service Center In Chennai

    ReplyDelete
  24. Iphone Service Center in Chennai

    We are the best Iphone service center in Chennai, we provide services with professionally trained Iphone mobile workers

    Iphone service center in chennai
    Apple Iphone Service Center In Chennai
    Apple Iphone Service Center In Chennai

    ReplyDelete
  25. Oneplus Service Center in Bangalore

    Oneplus Repair Service Center in Bangalore. For the finest service and fastest delivery for your Oneplus mobile, visit us! Go home a happy customer! Connect with us!!

    Oneplus Mobile Service Center in Bangalore

    ReplyDelete