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PONHibernate - How do I use a sum project on paged results
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  1. PONHibernate - How do I use a sum project on paged results
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    copied!<p>I'm trying to use paging in conjunction with a sum projection to get a sum of the values in a column for just the page of results I'm interested in. I'm using .NET, C# and NHibernate 3.1</p> <p>I have an ICriteria to start with which is related to all rows from the associated db table.</p> <p>I'm then doing the following to get a version with the first page (say, 10 items out of 40):</p> <pre><code>ICriteria recordsCriteria = CriteriaTransformer.Clone(criteria); recordsCriteria.SetFirstResult(0); recordsCriteria.SetMaxResults(10); </code></pre> <p>I'm using this ICriteria for something else so I then create two further clones:</p> <pre><code>ICriteria totalAggCriteria = CriteriaTransformer.Clone(criteria); ICriteria pageAggCriteria = CriteriaTransformer.Clone(recordsCriteria); </code></pre> <p>If I take a look inside these two new ones the first has 40 items in and the second has 10 - exactly what I want.</p> <p>Let's say the objects coming back from the DB have a column called "ColA" and it's of type <code>Int32</code>.</p> <p>From this, I want the sum of all 40 ColA values and the sum of the first 10 ColA values.</p> <p>To get the sum of all 40 ColA values, I do the following:</p> <pre><code>totalAggCriteria.SetProjection(NHibernate.Criterion.Projections.Sum("ColA")); var totalSum = totalAggCriteria.UniqueResult(); </code></pre> <p>The value in totalSum is correct.</p> <p>To get the sum of the first 10 ColA values, I'm trying the following:</p> <pre><code>pageAggCriteria.SetProjection(NHibernate.Criterion.Projections.Sum("ColA")); vat pageSum = pageAddCriteria.UniqueResult(); </code></pre> <p>However, this gives me the same value as the previous one - for all 40 ColA values.</p> <p>I've also tried the following but it gives the same result:</p> <pre><code>pageAggCriteria.SetProjection(NHibernate.Criterion.Projections.Sum(column)); pageAggCriteria.SetFirstResult(firstResult.Value); pageAggCriteria.SetMaxResults(pageSize.Value); pageSum = pageAggCriteria.UniqueResult(); </code></pre> <p>And also:</p> <pre><code>pageAggCriteria.SetFirstResult(firstResult.Value); pageAggCriteria.SetMaxResults(pageSize.Value); pageAggCriteria.SetProjection(NHibernate.Criterion.Projections.Sum(column)); pageSum = pageAggCriteria.UniqueResult(); </code></pre> <p>Can anyone give an idea on where I'm going wrong and how I can actually get the sum of the ColA values in the first 10 results?</p> <p>Thanks </p>
 

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