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linq to sql vb.net case statements in select and order by

Posted on 2009-07-09
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Last Modified: 2013-11-11
Hi all. I am trying to use linq to do a case statement in the order by but the problem is i have a custom column names that i want to sort on.  The only way i could get it to work was by writing another statement to sort the x variable into a new variable of z then i use that to bind to a dropdownlist as it is sorted as i want. But surely there is a better way of doing this than with 2 statements!

Thanks in advance for any help...


Dim x = From y In db.TicketSources Join pu In  db.tbO2PortalUsers On y.O2PortalUserID Equals pu.fdID _
                   Select New With {.value = y.TicketSourceID, .Text = If(y.O2PortalUserID <> 0 And pu.Active = 1, pu.FirstName & " " & pu.LastName, y.SourceName)} 
 
Dim z = From s In x Order By s.Text Ascending
 
 
return z.toList()  'the sorted list

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Question by:philipeharris
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Expert Comment

by:Bob Learned
ID: 24819540
I know that you can use extension methods to sort, like in this article:

Custom sorting order in LINQ (ORDER BY WEIGHTING)
http://www.daniel-skinner.co.uk/custom-sorting-order-in-linq-order-by-weighting/18/03/2009

But, I don't know the VB.NET-equivalent syntax for that kind of extension method.
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Expert Comment

by:CodeCruiser
ID: 24821193
I am not sure about the ASP.NET dropdownlist but winforms version has a Sorted property.
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by:philipeharris
ID: 24821426
Thanks both for you comments.

TheLearnedOne: i had seen those sorts during my extensive google searches, but i was hoping i could write the cope all in one statement like you can in actual SQL. Anyhow thanks for your reply.

CodeCruiser: No such property that i can find in asp.net VB version anyhow but again thankyou for your reply
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LVL 96

Expert Comment

by:Bob Learned
ID: 24840094
I was able to sort a simple Select with an "Order By" clause:


        Dim db As New AdventureWorksDataContext()
 
        Dim q = From x In db.Products _
            Where x.Name.StartsWith("Road-650") _
            Order By x.Name _
            Select x
 
        Dim sb As New StringBuilder()
 
        For Each product As Product In q
            sb.Append(product.Name & vbCr & vbLf)
        Next

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by:philipeharris
ID: 24847576
Thanks thelearnerone but that is an order by on a tables column name as apposed to what i was trying which was on a custom column name.  The order by for what i need would be the same as the select but its not possible as far as i can make out.

Thanks for your help.
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LVL 96

Expert Comment

by:Bob Learned
ID: 24849186
Oh, yeah, custom column name.  I got lost in a context switch (d'oh).

I don't see a way to order by a custom column name, but that doesn't mean that there isn't a way, just that I don't know every subtle nuance of LINQ.
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Accepted Solution

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philipeharris earned 0 total points
ID: 25096203
I dont think it should be deleted. If wanted it could be closed as nobody was able to give a better solution than that i gave in the question.
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