Hi,
I have a many-to-many relation with 3 tables (quite common). Everything works great. In the mapping file I specify this as a Set and therefore my class uses the Iesi ISet interface.
I am iterating through the elements of this set and building a table on a web page. The table contains a row for each element. But sometimes element A is before element B and vice versa.
This is a really annoying behaviour and I know that the reason for this is the ISet.
How can I assure a non-changing order of my elements?
I really like to use a Set and not a Bag.
Thank you

A set by definition does not define a specific order, however you may use the sort or order-by attributes in the <set> element in your mapping file to specify a specific sort order.

Alternatively you could use a list mapping, but that would involve adding a "position" column in your join table and chaing your ISet interface to IList.

Using a "order-by" in my mapping file helped to have a non-changing sort order.
I am wondering why the sort order is changing anyway? I am not modifying my elements. What makes the ISet return my elements in a different order if the circumstances are the same? It's kind of non-deterministic.
Thanks so far!

Because by definition relations (tables) are unordered sets of rows. Since they aren't required to, almost no RDBMS that I know of makes any guarantee about the ordering of rows returned to an unordered query, even sequential calls of the same query.

It's probably deterministic on some level, but not one readily visible to you or me.

As a side note, I've also used "order-by" to great effect. Quite handy. I have never used "sort", however. Just seems easier to let the database do the work whenever possible.