Implementing a BUDDY list

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  • David
    #1

    Implementing a BUDDY list

    I am creating a web community site where each user can have a list of
    buddies. I have struck a bit of a problem though.
    I am designing my db model and have two entities called users
    containing usual stuff like password, name... and I have Buddy List.
    I also have the following relation.

    Users "have a" Buddy List

    The cardinality is that a user can have one buddy list and one buddy
    list is associated with one user.

    However a buddy list contains MANY users and a single user can be in
    MANY buddy lists. So do I have a many-to-many relationship? To further
    confuse matters as a Buddy List is actually just a list of users is
    this a recursive relationship?

    Im really confused, any help welcomed!!!
    Tags: None
    • D. Pickering
      #2
      Re: Implementing a BUDDY list

      you need 2 tables. A user table (as you have described) and a buddy table
      with basically 2 columns. UserID, BuddyID.
      So if user 2 has buddies 4,5,8, 17 then there would be 4 rows in the buddy
      table
      2,4
      2,5
      2,8
      2,17
      to list 2's buddies
      select * from buddy where UserID=2. (gives you id's of 2's buddies)
      or select * from buddy left join users using (UserID)
      or select user.name as Uname from buddy left join users using (UserID) and
      the Uname(s) are 2's buddies.
      dp
      [color=blue]
      > I am creating a web community site where each user can have a list of
      > buddies. I have struck a bit of a problem though.
      > I am designing my db model and have two entities called users
      > containing usual stuff like password, name... and I have Buddy List.
      > I also have the following relation.
      >
      > Users "have a" Buddy List
      >
      > The cardinality is that a user can have one buddy list and one buddy
      > list is associated with one user.
      >
      > However a buddy list contains MANY users and a single user can be in
      > MANY buddy lists. So do I have a many-to-many relationship? To further
      > confuse matters as a Buddy List is actually just a list of users is
      > this a recursive relationship?
      >
      > Im really confused, any help welcomed!!![/color]


        Comment

        • D. Pickering
          #3
          Re: Implementing a BUDDY list

          you need 2 tables. A user table (as you have described) and a buddy table
          with basically 2 columns. UserID, BuddyID.
          So if user 2 has buddies 4,5,8, 17 then there would be 4 rows in the buddy
          table
          2,4
          2,5
          2,8
          2,17
          to list 2's buddies
          select * from buddy where UserID=2. (gives you id's of 2's buddies)
          or select * from buddy left join users using (UserID)
          or select user.name as Uname from buddy left join users using (UserID) and
          the Uname(s) are 2's buddies.
          dp
          [color=blue]
          > I am creating a web community site where each user can have a list of
          > buddies. I have struck a bit of a problem though.
          > I am designing my db model and have two entities called users
          > containing usual stuff like password, name... and I have Buddy List.
          > I also have the following relation.
          >
          > Users "have a" Buddy List
          >
          > The cardinality is that a user can have one buddy list and one buddy
          > list is associated with one user.
          >
          > However a buddy list contains MANY users and a single user can be in
          > MANY buddy lists. So do I have a many-to-many relationship? To further
          > confuse matters as a Buddy List is actually just a list of users is
          > this a recursive relationship?
          >
          > Im really confused, any help welcomed!!![/color]


            Comment

            • David
              #4
              Re: Implementing a BUDDY list

              thanks a lot!

                Comment

                • David
                  #5
                  Re: Implementing a BUDDY list

                  thanks a lot!

                    Comment

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