Linq To Sql Nested Select

Question

This is the SQL query I am trying to write with LINQ:

SELECT pd.Description, pd.Name, pd.SKU, pt.FileName,
(SELECT ISNULL(M1.parent, '') + '/' + M2.parent + '/' + M2.slug
    FROM seo AS M1
    JOIN seo AS M2
    ON M1.Slug = M2.Parent
    WHERE M2.SeoId = pd.seoId) as Url
FROM SEO seo
INNER JOIN Products p on seo.SeoID = p.SeoID
INNER JOIN RelatedProducts rp on p.ProductID = rp.ProductID
INNER JOIN Products pd on rp.RelatedID = pd.ProductID
INNER JOIN ProductPhotos pp on pd.ProductID = pp.ProductID
INNER JOIN Photos pt on pp.PhotoID = pt.PhotoID
WHERE seo.slug = 'SlugValue'

This is the LINQ I have:

_database.SEODataSource
                .Join(_database.ProductDataSource, seo => seo.SeoID, p => p.SeoID, (seo, p) => new { seo, p })
                .Join(_database.RelatedProductDataSource, @t => @t.p.ProductID, rp => rp.ProductID, (@t, rp) => new { @t, rp })
                .Join(_database.ProductDataSource, @t => @t.rp.RelatedID, pd => pd.ProductID, (@t, pd) => new { @t, pd })
                .Join(_database.ProductPhotoDataSource, @t => @t.pd.ProductID, pp => pp.ProductID, (@t, pp) => new { @t, pp })
                .Join(_database.PhotoDataSource, @t => @t.pp.PhotoID, pds => pds.PhotoID, (@t, pds) => new { @t, pds })
                .Where(@t => @t.@t.@t.@[email protected] == slug)
                .Select(@t => new ProductLinkDTO
                {
                    ProductDesc = @t.@[email protected],
                    ProductName = @t.@[email protected],
                    ProductSku = @t.@[email protected],
                    ProductImageName = @t.pds.FileName,
                    ProductUrl =  (_database.SEODataSource.Join(_database.SEODataSource, seo1 => seo1.SeoID, seo2 => seo2.SeoID, (seo1, seo2) => new {seo1, seo2})
                                  .Where(@t1 => @t1.seo2.SeoID == @t.@t.@t.@[email protected])
                                  .Select(@t1 => @t1.seo1.Parent ?? "" + "/" + @t1.seo2.Parent + "/" + @t1.seo2.Slug)).FirstOrDefault()
                }).ToList());

This is the query it produces:

SELECT [t3].[Name] AS [ProductName], [t3].[Description] AS [ProductDesc], [t3].[SKU] AS [ProductSku], [t5].[FileName] 
AS [ProductImageName], (
    SELECT TOP (1) [t8].[value]
    FROM (
        SELECT COALESCE([t6].[Parent],((@p1 + [t7].[Parent]) + @p2) + [t7].[Slug]) AS [value], [t7].[SeoID]
        FROM [dbo].[SEO] AS [t6]
        INNER JOIN [dbo].[SEO] AS [t7] ON [t6].[SeoID] = [t7].[SeoID]
        ) AS [t8]
    WHERE [t8].[SeoID] = [t0].[SeoID]
    ) AS [ProductUrl]
FROM [dbo].[SEO] AS [t0]
INNER JOIN [dbo].[Products] AS [t1] ON ([t0].[SeoID]) = [t1].[SeoID]
INNER JOIN [dbo].[RelatedProducts] AS [t2] ON [t1].[ProductID] = [t2].[ProductID]
INNER JOIN [dbo].[Products] AS [t3] ON [t2].[RelatedID] = [t3].[ProductID]
INNER JOIN [dbo].[ProductPhotos] AS [t4] ON [t3].[ProductID] = [t4].[ProductID]
INNER JOIN [dbo].[Photos] AS [t5] ON [t4].[PhotoID] = [t5].[PhotoID]
WHERE [t0].[Slug] = @p0',N'@p0 nvarchar(4000),@p1 nvarchar(4000),@p2 
nvarchar(4000)',@p0=N'KBUIT4255E-42in-Masterpiece-Side-By-Side',@p1=N'/',@p2=N'/'

Any idea what I am doing wrong?

Paul · Accepted Answer · 2010-08-03 02:01:56Z

3

By changing this:

.Select(@t1 => @t1.seo1.Parent ?? "" + "/" + @t1.seo2.Parent + "/" + @t1.seo2.Slug)).FirstOrDefault()

To:

.Select(@t1 =>  String.Concat(@t1.seo1.Parent ?? "", "/", @t1.seo2.Parent, "/", @t1.seo2.Slug))).SingleOrDefault()

The correct SQL was generated.

answered Aug 3, 2010 at 2:01

Paul

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