Re: Dumb Database schema / EOModeler questions...

Hi,

     I wonder, i need some more time to answer your first part of the req.
But regarding the second part i.e. story fetching i guess the following will
help you,

STORY:
StoryId - PK
CreatorId - FK 

 RelationShips:
 Creator - CreatorId --> UserId(UserId PK  of USER)

so when you want to fetch the stories written by the friends of user, form a
fetch specification such that it forms like,

select * from STORY where CreatorId in(select User2ID from FRIEND where
User1ID = the main user )

build the qualifier regardingly.

Build a EOKeyValueQualifier which is framed like "User2ID" equals "User1ID".
similarly create a  new EOKeyValueQualifier  which is framed like
"approvedByEditor" equals "true". Then from the userslist just use the
filterArrayWithQualifier using the final EOAndQualifier. This will give you
the list wanted.

I guess the DB you are using is oracle. if so, why did you choose storyId
etc. to LONGINT. will the Int not suffice your requirement?

I guess this leads to no duplication, 'coz the  userids we are using are
anyhow the PKs of the USER table. Dont forgot to have a instance variable
for the USERID in USER table in EOModel.

Regards,
Thrinath.J


Numair Faraz wrote:
> 
> Hi all,
> 
> I'm working on a "social news" application written in WO, and am
> currently in the process of modeling my database (we're going to use
> FrontBase).  As I am not an expert at database modeling / creating
> scalable solutions - embarrassingly bad, to tell you the truth - I
> wanted to get some perspectives from the people on the list regarding
> what they'd do.  My proposed implementations seem awfully simplistic,
> which leads me to believe that they won't scale ...
> 
> Basically, we have three tables: USER, FRIEND, STORY; what I want to
> figure out is...
> 
> - What is the most efficient way to set up the FRIEND table?  Assuming
> that when a user first asks to be a friend of another user, the
> connection remains pending until the other user confirms (thus meaning
> all USER.friends relationships are bi-directional), should I have
> things set up so that FRIEND is as such:
> 
> FRIEND
> ======
> friendId - LONGINT, Primary Key
> userId - LONGINT, Foreign Key
> user2Id - LONGINT, Foreign Key
> approved - BOOLEAN
> 
> owner - relationship to USER: FRIEND.userId + USER.userId
> friend - relationship to USER: FRIEND.user2Id + USER.userId
> 
> .. with an approval by the other user meaning that another FRIEND
> entry for their relationship?  I am assuming that two transactions /
> table entries are very inefficient, and that this will cause problems
> for me later on, but that's the best solution I could think of.
> 
> Now, assuming that we have USERs and USER.friends .. Say we have the
> following STORY table:
> 
> STORY
> ======
> storyId - LONGINT, Primary Key
> userId - LONGINT, Foreign Key
> body - CLOB
> approvedByEditor - BOOLEAN
> 
> author - relationship to USER: STORY.userId + USER.userId
> 
> .. How would one fetch all of the stories posted by the friends of a
> user in the most efficient manner?  My avoidance of reading a proper
> database modeling book has caused me to be incapable of even beginning
> to figure this out, let alone figure out how I would model it in
> EOModeler (blame the US education system...).  I also need to figure
> out how to fetch an array that contains both a user's friend's
> stories, and stories that are marked approvedByEditor, with no
> duplication; again, no clue how I would do this in EOModeler (which I
> hadn't used in about 4 years, until this week)...
> 
> Hope you guys can help ...
> 
> Numair
> _______________________________________________
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> 
> 

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