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RDot
 Post subject: DateDiff and DetachedCriteria
PostPosted: Thu Aug 21, 2008 9:59 am 
Newbie

Joined: Mon Jul 21, 2008 3:01 pm
Posts: 7
I have read the manual, searched the faq's and web to no avail. If you can point me to a specific document regarding an answer please do. Thanks!

I want to use a DetachedCriteria for the following SQL statement. I don't want to use any HQL or SQL.

Code:
select *
from [AnyTable]
where DateDiff(dd,[AnyDateField],getdate()) >[SomeIntegerValue]



Simply I want to tell if the number of days between today and a date field is greater then some value.

NOTES:
-- I'm using Nhibernate 1.2.1 GA.
-- I'm using SQL Server 2005.
-- Visual Studio 2005

Thanks -
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RDot
 Post subject:
PostPosted: Thu Aug 21, 2008 12:14 pm 
Newbie

Joined: Mon Jul 21, 2008 3:01 pm
Posts: 7
I decided to do the following approach. If anyone has a better solution let me know. Thanks!

In my hibernate mappng file I created a new property..

Code:
<property name="DaysCheckedOut" formula="DateDiff(dd,CheckedOutOn,getdate())" />


Using the DetachedCriteria now yields a statement like..

Code:
detachedCriteria.Add(new NHibernate.Expression.GtExpression("DaysCheckedOut", 50));


The only problem with my approach is I really only need the DaysCheckedOut property when a user filters by this field. Since I made it a class property it will now always be part of the query when retrieving data. Not a huge performance penalty but I'd rather not always pull the field.

[/code]
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RDot
 Post subject:
PostPosted: Thu Aug 21, 2008 1:04 pm 
Newbie

Joined: Mon Jul 21, 2008 3:01 pm
Posts: 7
My solution does not work as NHibernate is trying to replace the 'dd' in the DateDiff function withe a field name from my table. Will continue to research just didn't want to lead anyone down the wrong path.
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RDot
 Post subject:
PostPosted: Thu Aug 21, 2008 2:28 pm 
Newbie

Joined: Mon Jul 21, 2008 3:01 pm
Posts: 7
ok, figured out a solution. I'm not overly thrilled with my solution but based on my current level of experience here it is...


Code:
dc.Add(Expression.Sql("(DateDiff(dd,CheckedOutOn,getdate()) >=" + rFilter.FieldValue + ")"));


Where dc is an instance of a DetachedCriteria object and CheckedOutOn is a field from my database.

The reason i'm not overly excited about this solution is i'm hard-coding SQL when I really want to use the criteria API.

So I did not add a new field to my xml mapping file or my class.
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