relationship m:n

[Rodolfo García Esteban/CYII <rg...@cyii.es>]

Hi all,

I have an relationship m:n in my object model, this is implemented by a 
relationship table. And I'm thinking what would be the correct way to 
implement inserts and updates in this relationship table.

I would appreciatte all opinios.

Thanks

Rodolfo
________________________

RE: relationship m:n

[Meindert <me...@pastelebusiness.com>]

I would:

 

Assume you have m:n relation between classroom and students;

You would probably have a classroom object containing a list with students

(And a student object containing a list of classrooms)

 

When persisting the classroom I would (in a transaction)

update the classroom (or insert when classroom_ID==null) 

walk through the list of Students and insert the new students (when
student_ID==null)

(retrieve the generated ID of the new Students)

remove all (old) related Students out of the relationship table

insert all the related student_ID’s from the list

 

Don’t know if it’s right, but it works fine for me :-)

Also tried a way so I didn’t have to delete and insert the same record;

- Add a deleteMe flag to the relationtable

 

When doing the persisting set all the deleteMe ‘sto true for the current
classroom

Walk through the list of students and update the flag to false of the
relation table

If no rows where updated insert a row

Delete all rows where deleteMe is true

 

 

MEINDERT HOVING



   _____  

From: Rodolfo García Esteban/CYII [mailto:rgarciaesteban@cyii.es] 
Sent: 25 January 2006 02:56 PM
To: user-java@ibatis.apache.org
Subject: relationship m:n 

 


Hi all, 

I have an relationship m:n in my object model, this is implemented by a
relationship table. And I'm thinking what would be the correct way to
implement inserts and updates in this relationship table. 

I would appreciatte all opinios. 

Thanks 

Rodolfo
________________________

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