SSRS distinct lookupset function - reporting-services

Question

I'm using Join(Lookupset) to find unique group values which returns a sequence number. This is my function:
Join(LookupSet(Fields!itemId.Value & Fields!UseByDate.Value & Fields!rackId.Value
, Fields!itemId.Value & Fields!UseByDate.Value & Fields!rackId.Value
, Fields!CustomerSeqNo.Value
, "PickingList"), ",")
The problem is on some items there are multiple transactions. I want to remove the duplicates.
I found a blog http://blogs.msdn.com/b/bobmeyers/archive/2012/06/18/creating-short-lists-using-the-lookupset-function.aspx but could not get SSRS Report Builder to reference Linq assembly. My issue is
How can I just show the unique values?

Answer 1

You don't need Linq, but you do still need custom code (in BIDS go to Report -> Report Properties -> Code)
You can put a RemoveDuplicates function in here, something like this:
Public Shared Function RemoveDuplicates(m_Array As Object()) As String()
System.Array.Sort(m_Array)
Dim k As Integer = 0
For i As Integer = 0 To m_Array.Length - 1
If i > 0 AndAlso m_Array(i).Equals(m_Array(i - 1)) Then
Continue For
End If
m_Array(k) = m_Array(i)
k += 1
Next
Dim unique As [String]() = New [String](k - 1) {}
System.Array.Copy(m_Array, 0, unique, 0, k)
Return unique
End Function
To use it in your Join:
Join(Code.RemoveDuplicates(LookupSet(...)),",")

Answer 2

I agree with #user3697615 that Report Code is best. However, I prefer to build it straight into a string:
public shared function JoinDistinct(
dups as object(),
delimiter as string
) as string
dim result as string = ""
system.array.sort(dups)
for i as integer = 0 to dups.length - 1
if i <> 0 then result += delimiter
if i = 0 orElse dups(i) <> dups(i-1) then result += dups(i)
next i
return result
end function
This way, we eliminate one nested function on the call:
=Code.JoinDistinct(LookupSet(...), ",")

Answer 3

If you're like me, you also want the elements in order based on frequency (descending order).
I created the following VisualBasic code to do so
Public Shared Function RemoveDuplicates(dataset As Object()) As String()
Dim unique As New System.Collections.Generic.List(Of String)
Dim frequency As New System.Collections.Generic.List(Of Integer)
For i As Integer = 0 To dataset.Length - 1
Dim index As Integer = -1
For j As Integer = 0 To unique.Count - 1
If dataset(i).Equals(unique(j)) Then
index = j
Exit For
End If
Next
If index < 0 Then
unique.Add(dataset(i))
frequency.Add(1)
Else
frequency(index) += 1
End If
Next
Dim uniqueArray As [String]() = unique.ToArray()
Array.Sort(frequency.ToArray(), uniqueArray)
Array.Reverse(uniqueArray)
return uniqueArray
End Function
This is based off others' answers where the SSRS expression is the following
Join(Code.RemoveDuplicates(LookupSet(...)),",")
Note: I learned VisualBasic in about an hour to solve this problem, so my algorithm probably isn't the most efficient.

Answer 4

I liked pwilcox's idea, so I wrote this one which filters out null and blank values.
Public Function JoinDistinct(arr As Object(), delimiter As String) As String
System.Array.Sort(arr)
Dim result As String = String.Empty
Dim lastvalue As String = String.Empty
For i As Integer = 0 To arr.Length - 1
If Not arr(i) Is Nothing And arr(i) <> lastvalue And arr(i) <> String.Empty Then
If result = String.Empty Then
result = arr(i)
Else
result = result + delimiter + arr(i)
End If
End If
lastvalue = arr(i)
Next
Return result
End Function
Usage:
=Code.JoinDistinct(LookupSet(...), ",")