I was hoping to tap the collective wisdom for an alternative to a join
with a condition.
Here is my scenario:
We have a long-term care application. I have a person entity. That
person should have a property indicating where they are currently
located (which bed they are in). Beds can (and do) change people
occasionally. The history of all the people who have been in any bed
in is in a table, including the current occupant. The current bed is
indicated by a null value in the "END_DATE" field of the bed table
(The bed/person relationship hasn't ended because the person is still
in the bed). So, the only way to get the current bed property is to
join the person table and the bed table on the person id where
end_date is null.
Unfortunately, it looks like NHibernate doesn't support join
conditions. And I understand that this isn't the best design, but
we're writing against a vendor supplied application.
Does anyone here have any examples of similar implementations and what
you've done to get around it? We're writing an application that
presents reports, and current live information in a nicer UI. This app
will be written against 2, possibly 3 different vendor databases
depending on the facility (they all use different tracking apps). So,
we've been trying to keep our entity design database agnostic. It
looks like that isn't possible, as I'm likely going to need to setup
some middle-men entities to represent the current structure. Any
ideas?
Entity:
public class person
{
public virtual int id { get; set; }
public virtual string name { get; set; }
public virtual room {get; set; }
}
Table Person:
ID Name Room
1 Bob 132
2 Hal 203
Table Room_history
Room person_id date_start date_end
132 5 1999/12/23 2003/5/13
132 8 2003/5/14 2008/1/21
132 1 2008/1/22 NULL
203 23 1999/12/23 2002/3/30
203 2 2002/4/1 NULL
- Randall
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