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  1. #1
    Join Date
    Jan 2009
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    10

    Question Unanswered: some explanation about database normalization

    have some doubt at ths point :
    2NF:Table should be in 1nf+no partial function dependencies.

    3nf:Table should be in 2nf+No transitive dependencies.
    can you explain this two line only

  2. #2
    Join Date
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    Where the Surf Meets the Turf @Del Mar, CA
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    Provided Answers: 1
    You can lead some folks to knowledge, but you can not make them think.
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    For most folks, they don't know, what they don't know.
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  3. #3
    Join Date
    Jan 2009
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    10

    Question

    2NF:Table should be in 1nf+no partial function dependencies.
    3nf:Table should be in 2nf+No transitive dependencies.can you explain this two line only.Kindly give Some Explanation please.can you tell me please .meaning of Transitive Dependencies Here.
    Last edited by firoz.raj; 11-19-09 at 01:21.

  4. #4
    Join Date
    Aug 2009
    Posts
    262
    A table is in second normal forum (2nf) if :
    - It is in !NF
    and
    -It includes no partial dependencies; that is , no attributes is dependent on only a portion of the primary key.
    ( but it is still possible for a table in 2NF to exhibit transitive dependency; that is, one or more attributes may be functionally dependent of nonkey attributes.)


    A table is in third normal form (3NF) if;
    -it is in 2NF.
    and
    - it contains no transitive dependencies.


    Transitive Dependency.

    column:
    Empno | Job class | CHA_hour
    1 | database admin | $105.00
    2 | programmer | $35.00

    Note that cha_hour is dependent on Job_vlass . because neither cha_hour nor Job_class is a prime attribute( as there can be many persons with same job class)
    that is neither attribute is at least part of a key - we have a condition known as transitive dependency. ( In other words , a transitive dependency is a dependency of one nonprime attribute on another nonprime attribute). And the problem with transitive dependencies is that they still yield data anomalies.

  5. #5
    Join Date
    Jan 2009
    Posts
    10

    Question

    In the attachment i have included Order and detail table.Can you tell me please it contains.Transitive dependencies or not.or it is Fully In 3nf
    Kindly let me know the idea.Any help would be highly appreciated.
    Attached Thumbnails Attached Thumbnails OrderTable.jpg   Detail.jpg  

  6. #6
    Join Date
    Aug 2009
    Posts
    262
    a quick look . i dont see any key attributes defined .

    would be much easier to answer if you had provided ddl of tables

  7. #7
    Join Date
    Jan 2009
    Posts
    10

    Question

    Kindly find the DDL.JPG.Kindly let me know the idea.kindly let me know .How it
    don't obey transitive dependencies.means it is in 3NF.Any help would be highly
    appreciated.
    Attached Thumbnails Attached Thumbnails ddl.jpg  

  8. #8
    Join Date
    Aug 2009
    Posts
    262
    you are asking micorsoft access question in ORACLE forum ? .

    I have no experience of access and GOD knows i love oracle .

    let me give you a simple vision of it . key attribute is considered enforced by primary key column . ( letting out any referential ) . i see key icons beside the colums but when i see the data of those columns i see non unique values . no sequential and disturbed .

    how am i going to explain any thing to you when in my humble limited opinion i dont see any thing to explain

  9. #9
    Join Date
    Jan 2009
    Posts
    10

    Question

    Can you tell me Some Good Website for Oracle Devloper means for Forms Reports and PlSql.Kindly let me know the Idea.Any help would be highly appreciated.

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