Announcement

Collapse
No announcement yet.

Normalization Steps

Collapse
X
  • Filter
  • Time
  • Show
Clear All
new posts

  • Normalization Steps

    During my degree career in computer science I have studies 5 normal form in database course. I have done many huge database projects and get full normalized form of my database at third stage and never came a time to use the fourth and fifth normal form. Any one in the forum who can guide me when fourth and fifth normal form of the data base is used?

  • #2
    The goal of a relational database design is to generate a set of relation scheme that allow us to store informastion easily. One approach is to design scheme that are in an appropriate normal form (silberschatz, H., 1991)
    We have to normalize the database in order to make it easier to maintain, develop, or to resolve the error.
    It will be several steps to do, but usually it just only need till the third step.

    Comment


    • #3
      Fourth And Fifth Normal Forms

      Fourth [5] and fifth [6] normal forms deal with multi-valued facts. The multi-valued fact may correspond to a many-to-many relationship, as with employees and skills, or to a many-to-one relationship, as with the children of an employee (assuming only one parent is an employee). By "many-to-many" we mean that an employee may have several skills, and a skill may belong to several employees.
      Last edited by Pegasus; 04-26-2014, 07:47 AM. Reason: spam signature removed by moderator

      Comment


      • #4
        Originally posted by SeoDezin View Post
        During my degree career in computer science I have studies 5 normal form in database course. I have done many huge database projects and get full normalized form of my database at third stage and never came a time to use the fourth and fifth normal form. Any one in the forum who can guide me when fourth and fifth normal form of the data base is used?
        4th Normal form:
        Suppose we have three fields Employee,Language and skill.Here two many to many relationship works.One employee can speak in many languages and one employee can have meny skills.

        EMPLOYEE | SKILL | LANGUAGE |

        But in case of 4th Normal form we have to represent it like

        -------------------- -----------------------
        | EMPLOYEE | SKILL | | EMPLOYEE | LANGUAGE |
        ___________________________________________________
        5th Normal form:
        Suppose a table has three field’s agents,company and product.Agent represents company,company produce product and products are sold by agents.

        AGENT | COMPANY | PRODUCT |
        |-------+---------+---------|
        | Smith | Ford | car |
        | Smith | GM | truck |
        -----------------------------

        In this case agent Smith is not selling Ford companies truck or GM company’s car.

        In this case we can classify a table likewise

        --

        ------------------ --------------------- -------------------
        | AGENT | COMPANY | | COMPANY | PRODUCT | | AGENT | PRODUCT |
        |-------+---------| |---------+---------| |-------+---------|
        | Smith | Ford | | Ford | car | | Smith | car |
        | Smith | GM | | Ford | truck | | Smith | truck |
        | Jones | Ford | | GM | car | | Jones | car |
        ------------------- | GM | truck | -------------------
        ---------------------

        Comment

        Working...
        X