Question

So I have a many to many relationship between something known as Specialism and SpecialismCombo. What I’m trying to do is take an int[] of ids and check if there is a combo already that contains the specialisms with those ids.

I was close but not quite right.
Say I have specialisms with Ids 1 and 3 and I create a combo with those specialisms.

If I pass in 3 & 1 then it returns the expected combo id.

If I pass in 1 then it returns the combo id that has both 1 and 3.

I can’t just rely on total number of specialisms associated with the combo. Because if a combo has two items, 1 and 4 and the items being matched on are 1 and 3 I don’t want this coming back as a matched combo.

So it’s like I do need the count of this result, and match the count of total specialisms associated to the combo. I don’t quite get whether I’m after a subquery or detatchedcriteria or how to get the result I want using nhibernate criteria. Thanks for your help!

int[] SpecialismIds = ArrayExtensions.ConvertArray<int>(idCollection.Split(new char[] { '|' }));

    ICriteria query = m_SpecialismComboRepository.QueryAlias("sc");
        query.CreateAlias("sc.Specialisms", "s", NHibernate.SqlCommand.JoinType.InnerJoin);

    ICriterion lastCriteria = null;

    foreach(int i in SpecialismIds)
    {

         ICriterion currentCriteria = Restrictions.Eq("s.SpecialismId", i);
        if (lastCriteria != null)
                        lastCriteria = Restrictions.Or(lastCriteria, currentCriteria);
                    else
                        lastCriteria = currentCriteria;
    }

    if (lastCriteria != null)
                    query.Add(lastCriteria);

    IProjection IdCount = Projections.Count("s.SpecialismId").As("IdCount");

    query.SetProjection(
        Projections.GroupProperty("sc.SpecialismComboId"),
        IdCount 
        );

    query.Add(Restrictions.Eq(IdCount, SpecialismIds.Count()));

    var comboId = query.List();

The sql being generated is:

SELECT this_.SpecialismComboId as y0_, count(s1_.SpecialismId) as y1_ 
FROM dbo.SpecialismCombo this_ 
inner join SpecialismComboSpecialism specialism3_ on this_.SpecialismComboId=specialism3_.SpecialismId 
inner join dbo.Specialism s1_ on specialism3_.SpecialismComboId=s1_.SpecialismId WHERE s1_.SpecialismId = @p0 
GROUP BY this_.SpecialismComboId HAVING count(s1_.SpecialismId) = @p1',N'@p0 int,@p1 int',@p0=3,@p1=1

EDIT – It seems like I either need the having to be something like…

HAVING count(s1_.SpecialismId) = (select count(SpecialismId)
from specialismComboSpecialism
where SpecialismComboId = y0
group by SpecialismComboId) == @p2

Or maybe it’s simpler than that and I need to exclude SpecalismCombos where the combo.specialisms are not in the collection of ids.

Ie. if the combo has specialisms 1 and 3 but the collection only has 1.. then we could exclude this combo based on 3 not being in the collection…

Edit 8/8/2011
Went back to focusing on how to get the result I needed in SQL – and I believe this query works.

WITH CustomQuery AS
        (
        SELECT sc.SpecialismComboId,
        count(s.SpecialismId) AS ItemCount
        FROM SpecialismCombo sc 
        inner join SpecialismComboSpecialism scs on sc.SpecialismComboId = scs.SpecialismComboId
        inner join Specialism s on s.SpecialismId = scs.SpecialismId
        GROUP BY sc.SpecialismComboId 
        HAVING count(s.SpecialismId) = 2
        )

        SELECT CustomQuery.SpecialismComboId FROM CustomQuery
        INNER JOIN SpecialismComboSpecialism scs on CustomQuery.SpecialismComboId = scs.SpecialismComboId
        WHERE scs.SpecialismId in (1,4)
        GROUP BY CustomQuery.SpecialismComboId 
        HAVING count(scs.SpecialismId) = 2

So now I just need to figure out how to call this procedure from my nhibernate code passing in the appropriate values 🙂

I also discovered in the process that my mapping class was wrong – as it was putting the wrong values in the mapping table (ie. the specialismid was ending up in the specialismcomboid field !)

Answer 1

So I ended up creating a stored proc and using SQL CTE in order to get only the specialism combos with the correct count of specialisms. Posting this in case someone else comes across a similar issue.

Rediscovered after 8 months of using nhibernate that I’d forgotten a lot of SQL stuff 🙂

 DECLARE @IdCollectionCount         INT
    , @IdCollection             VARCHAR(250)
    , @CollectionDelimiter      NVARCHAR

    SET @IdCollectionCount = 2;
    SET @IdCollection = '1,4';
    SET @CollectionDelimiter= ',';

    WITH CustomQuery AS
        (
        SELECT sc.SpecialismComboId,
        count(s.SpecialismId) AS ItemCount
        FROM SpecialismCombo sc 
        inner join SpecialismComboSpecialism scs on sc.SpecialismComboId = scs.SpecialismComboId
        inner join Specialism s on s.SpecialismId = scs.SpecialismId
        GROUP BY sc.SpecialismComboId 
        HAVING count(s.SpecialismId) = @IdCollectionCount
        )

        SELECT Top 1 CustomQuery.SpecialismComboId FROM CustomQuery
        INNER JOIN SpecialismComboSpecialism scs on CustomQuery.SpecialismComboId = scs.SpecialismComboId
        INNER JOIN dbo.fn_SplitDelimited(@IdCollection,@CollectionDelimiter) AS ids
              ON scs.SpecialismId = CAST(ids.ListValue AS INT)
        GROUP BY CustomQuery.SpecialismComboId 
        HAVING count(scs.SpecialismId) = @IdCollectionCount