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  1. #1
    Join Date
    Apr 2004
    Posts
    3

    Unanswered: Can anyone give nme example query that can't be expressed in relation algebra

    i create a database for video rental
    3 tables are

    Films (Film_No,Film_Name,Description)
    Members(Member_ID,Name,Address)
    RentalInfo(Fim_No,DateRented,DateReturn,RentalCost ,Member_ID)

    can anyone give me an example query that cannot be expressed in relational algebra?...and please tell me why it can't

  2. #2
    Join Date
    Mar 2004
    Location
    Toronto, ON, Canada
    Posts
    513

    Re: Can anyone give nme example query that can't be expressed in relation algebra

    Originally posted by anchana
    i create a database for video rental
    3 tables are

    Films (Film_No,Film_Name,Description)
    Members(Member_ID,Name,Address)
    RentalInfo(Fim_No,DateRented,DateReturn,RentalCost ,Member_ID)

    can anyone give me an example query that cannot be expressed in relational algebra?...and please tell me why it can't
    This sounds suspiciously like an exam question...
    --
    Jonathan Petruk
    DB2 Database Consultant

  3. #3
    Join Date
    Apr 2004
    Posts
    3

    Re: Can anyone give nme example query that can't be expressed in relation algebra

    he he...it is....but it is past exam paper...i am just curious to know

  4. #4
    Join Date
    Mar 2004
    Location
    Toronto, ON, Canada
    Posts
    513

    Re: Can anyone give nme example query that can't be expressed in relation algebra

    Originally posted by anchana
    he he...it is....but it is past exam paper...i am just curious to know
    According to my Fundamentals of Database Systems text, the following cannot be performed with standard relational algebra:

    Aggregate Functions (ie COUNT, MAX, MIN)

    Recursive Closure Operations (doesn't really apply to the tables you gave, but it would be answering questions like "show me all the employees under the President" where there are several levels of management.

    Arithmatic operations (+/-/*)

    Don't know if there are others, but that's what I've got
    --
    Jonathan Petruk
    DB2 Database Consultant

  5. #5
    Join Date
    Mar 2004
    Posts
    448
    Relational database has also its limitations.
    There is another forms of databases that are deducted databases or logical form of database
    and they have their own language.It has been at the masters level.
    I wll give you an example "how you find a location or map from any web site like mapquest"
    Deducted Databases is infact more powerful than relational databases

  6. #6
    Join Date
    Apr 2004
    Posts
    3
    Oh....Thank a lotttttttttttttttttttttttttt......

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