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From: "Matteo" <matteo@THRWHITE.remove-dii-this>
Subject: hibernate: mapping help
Message-ID: <g12f1t$aas$1@nnrp.ngi.it>
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Date: Wed, 27 Apr 2011 15:21:57 GMT
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Hello all,
I'm fairly new to hibernate, though I'm not new to ORM concepts.
I read the official h8 version 3 tutorial, as well as other articles and 
examples out there.

Now the problem is that I can't figure out how the best way to map the 
following tables:

table USERS (
    `userID` int(11) unsigned NOT NULL auto_increment,
    `name` varchar(255) NOT NULL,
    `lastName` varchar(255) NOT NULL,
    `nickname` varchar(20) NOT NULL,
    PRIMARY KEY  (`userID`),
    KEY `nickname`  (`nickname`)  ---> indice
)

table FRIENDS (
    `userID` int(11) unsigned NOT NULL default '0',
    `friendID` int(11) unsigned NOT NULL default '0',
    PRIMARY KEY (`userID`,`friendID`),
    KEY `friendID` (`friendID`),
    CONSTRAINT `friends_ibfk_1` FOREIGN KEY (`userID`) REFERENCES `users`
(`userID`),
    CONSTRAINT `friends_ibfk_2` FOREIGN KEY (`friendID`) REFERENCES `users`
(`userID`)
)

table MESSAGES (
    `messageID` int(11) unsigned NOT NULL auto_increment,
    `from` int(11) unsigned NOT NULL,
    `to` int(11) unsigned NOT NULL,
    `message` varchar(4000) default NULL,
    PRIMARY KEY (`messageID`),
    KEY `from` (`from`),
    KEY `to` (`to`),
    CONSTRAINT `messages_ibfk_1` FOREIGN KEY (`from`) REFERENCES `users`
(`userID`),
    CONSTRAINT `messages_ibfk_2` FOREIGN KEY (`to`) REFERENCES `users`
(`userID`)
)

I'm stuck with my implementation of the "friendship" relationship, as I 
decided to define it with a directed-graph, thus user.A and user.B are 
"friends" if and only if
( FRIENDS.userID = user.A ; FRIENDS.friendID = user.B ) AND  ( 
FRIENDS.userID = user.B ; FRIENDS.friendID = user.A )
Hence, the composite-id (userID, friendID) of FRIENDS table.

As for MESSAGES table, both FROM and TO fields referentiate USERS.userID 
(and I'm stuck with that too )


Thanks in advance !
Matteo

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