CODEWITHSUNDEEP
nhibernate
Mark Struzinski
Mark Struzinski

Reputation: 33481

What's the best way to get aggregate results from NHibernate?

For example, I am trying to get a min date, a max date, and a sum in different instances. I am trying to avoid hard coding a SQL string or looping through an IList to get these values.

Upvotes: 2

Views: 1913

Answers (2)

kͩeͣmͮpͥ ͩ
kͩeͣmͮpͥ ͩ

Reputation: 7846

If you need queries for reporting, use projections.

Something like: 

Session.CreateCriteria ( typeof ( Order ) )
            .Add ( Restrictions.Between ( "DateReceived" , today.AddMonths ( -1 ) , today ) )
            .CreateAlias ( "Lines" , "lines" )
            .SetProjection (
            Projections.ProjectionList ( )
                .Add ( Projections.Sum ( "lines.TotalCost" ) )
                .Add ( Projections.Avg ( "lines.TotalCost" ) )
                .Add ( Projections.GroupProperty ( "Customer" ) )
            ) ;

There's more stuff in Nhibernate Documentation (it's 2/3 of the way down)

Upvotes: 2

mspmsp
mspmsp

Reputation: 955

You can run straight queries through NHibernate. Or add additional order by info so the resulting objects are in order via the parameter you're interested in. Order descending and your 0th element is what you want for max and mins. etc etc. There's more than one way to skin the hibernating cat.

Upvotes: 2

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