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  1. #1
    Join Date
    Jul 2005
    Posts
    29

    Unanswered: ISA relationship

    Hi,
    do you use ISA relationship or do you avoid it? Why?
    Could you write me some its benefitsand drowback?
    Thanks

  2. #2
    Join Date
    Apr 2002
    Location
    Toronto, Canada
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    20,002
    i guess i don't use it

    i don't even know what it is

    so that would be a drawback, i suppose
    rudy.ca | @rudydotca
    Buy my SitePoint book: Simply SQL

  3. #3
    Join Date
    Jul 2005
    Posts
    29
    ISA relationship(something like inheritance)

    Drowback can be more difficult query.

    Benefits ???

  4. #4
    Join Date
    Jan 2004
    Location
    In a large office with bad lighting
    Posts
    1,040
    Smells like homework.

    -- This is all just a Figment of my Imagination --

  5. #5
    Join Date
    Mar 2004
    Posts
    190
    If it smells like homework, and it looks like homework... chances are that it is homework.

    Perseus, I am sure that your friends at the International Society of Arboriculture will be disappointed that you are searching for a relationship elsewhere. Perhaps you should speak to them about the benefits drawbacks and reforestation. It might make you feel better. http://www.isa-arbor.com/french.aspx
    Last edited by msmeland; 05-21-07 at 10:23.
    "An adventure is only an inconvenience rightly understood; an inconvenience is only an adventure wrongly considered." ~G.K. Chesterton

  6. #6
    Join Date
    May 2004
    Location
    Seattle
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    1,313
    ISA is not a concept in SQL Server. t-sql is not a OO language.

    You are confusing your C++ class material with your SQL class material.

  7. #7
    Join Date
    Mar 2004
    Posts
    190
    OO jezemine, don't break the guys drowback... you know how sensitive dark elves can be.

    I C++ your point about his lack of class distinction, perhaps he just needs to straighten out his concepts to find the benefits.
    "An adventure is only an inconvenience rightly understood; an inconvenience is only an adventure wrongly considered." ~G.K. Chesterton

  8. #8
    Join Date
    Apr 2002
    Location
    Toronto, Canada
    Posts
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    you two seem to know what you're talking about, could you satisfy my curiosity and tell me what an ISA relationship is?

    oh, wait, never mind, i just found it in wikipedia, it's related to the HASA and USESA relationships

    perseus, i avoid the ISA relationship in my database designs

    i use NULL columns instead
    rudy.ca | @rudydotca
    Buy my SitePoint book: Simply SQL

  9. #9
    Join Date
    May 2004
    Location
    Seattle
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    say you have two classes, Animal and Dog. Dog derives from Animal. Dog ISA Animal.

    there's no notion of classes or inheritance in T-SQL so the OP question doesn't really make sense.

  10. #10
    Join Date
    Jul 2005
    Posts
    29
    (It is not homework.)
    It seems me that that solving has only all disadvantages.
    Do I mistake?

  11. #11
    Join Date
    Feb 2004
    Location
    One Flump in One Place
    Posts
    14,912
    From what I have gleened, an ISA relationship is not possible nor relevent in SQL Server. I would characterise this as its principal disadvantage. For the same reason, I typically avoid one.

    Do I get an A?
    Testimonial:
    pootle flump
    ur codings are working excelent.

  12. #12
    Join Date
    Mar 2004
    Posts
    190
    I give you an C++ Poots
    "An adventure is only an inconvenience rightly understood; an inconvenience is only an adventure wrongly considered." ~G.K. Chesterton

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