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  1. #1
    Join Date
    Oct 2003
    Posts
    8

    Unanswered: how to set tables

    hi

    can anyone tell me what is the easy way to learn the tables setup.
    I mean how to setup my tables for any application.

    example.
    say I want to develop a small appliction by using oracle for a car showroom, offcourse the first step is to set my tables.

    tables.
    1) customers
    2) cars
    3) transactions
    4) services
    5) etcc..

    so my question is what is the easy and best way to set and links the tables. if there is any site who is helping to learn this kind of basic help then please do inform me.

    thank you for your guidance..

  2. #2
    Join Date
    Nov 2003
    Location
    Bangalore, INDIA
    Posts
    333

    Thumbs up

    HI,

    Every database starts out as an entity-relationship diagram. In order to model a business process, the developers of an application must first map out the different components of a system. This map of a business process is often referred to as the entity-relationship diagram, or ERD for short. The ERD consists of two different components,

    Entity A person, place, thing, or idea involved in the business
    process flow
    Relationship The ties that bind entities together

    An entity-relationship diagram is helpful to understand the process flow of data through the system. Once an entity-relationship diagram is created, the developer must then create a special diagram that models the data stored in a database to represent the entities and relationships in the ERD. The name of this special diagram is "logical data model," or LDM for short. The LDM will be used to display how all data relating to the business process being modeled is stored in the database. A logical data model consists of a diagrammatic representation of tables in a database.

    In order to model data, there must be relationships between the various components that make up a database design. These components are stored as data, while the relationships between data can be defined explicitly via the use of integrity constraints and/or database triggers that model business rules, or implicitly by the data manipulation statements that select data for viewing or populate the database with new data.

    The first step in creating a list of table columns is to determine what will be the unique characteristic of any row in the table. THis is called as primary key. The determination about whether to incorporate data as a column into the table should rest on two conditions:

    1. Is this data functionally dependent on the primary key?
    2. Will there be only one copy of this data per appearance of the
    primary key?

    Each column that is not part of the primary key is considered to be "functionally dependent" on the primary key. This term simply means that the dependent column stores data that relates directly to or modifies directly each individual row.

    Once these factors are determined, the designer will know if he should include the column in the table or whether the column should be used to define another table. Data components that have no functional dependency to the other data in a table record should be placed in separate tables.

    Foreign-key relationship is often referred to as a parent/child relationship because of where the data must appear in each table to create the foreign-key relationship. In the "child" table, the data can appear either as part of the primary key or as a functionally dependent column. However, in the "parent" table, the referenced column must appear in the primary key.
    SATHISH .

  3. #3
    Join Date
    Oct 2003
    Posts
    8
    thanks satish_ct for your such a detail reply

    would you kindly guide me where I can find more help on this, any site?

  4. #4
    Join Date
    Nov 2003
    Location
    Bangalore, INDIA
    Posts
    333

    Cool

    Hi Aatish,

    You can get more info about this in OCP Application developer guide by Jason S. Couchman & Christopher Allen. You can also refer any DBMS book.
    SATHISH .

  5. #5
    Join Date
    Sep 2003
    Location
    NE Florida w/ view of co-workers
    Posts
    32
    I would recommend visiting a bookstore or library. A small investment in a book about database design will probably go a long way for you. You don't even need one specific to Oracle or any other database brand.

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