C# source code, for those that prefer to compile for themselves:

using System;

using System.Collections;

using System.Collections.Generic;

using System.Data.SqlTypes;

using Microsoft.SqlServer.Server;

public partial class UserDefinedFunctions

{

[SqlFunction

(

DataAccess = DataAccessKind.None,

SystemDataAccess = SystemDataAccessKind.None,

FillRowMethodName = "FillRow",

IsDeterministic = true,

IsPrecise = true

)

]

public static IEnumerable GetCombinations

(

[SqlFacet(MaxSize = 256, IsNullable = false, IsFixedLength = false)] SqlString input

)

{

// Check for a NULL parameter

if (input.IsNull)

{

return new string[0];

}

// Create a list of string arrays to hold each member of each group

List<string[]> groupList = new List<string[]>();

// Split the input into groups on the semicolon

string[] groups = input.Value.Split(new char[] { ';' }, StringSplitOptions.RemoveEmptyEntries);

// For each group, add each item of the group to a string array in the list

for (int i = 0; i < groups.Length; i++)

{

groupList.Add(groups.Split(new char[] { ',' }, StringSplitOptions.RemoveEmptyEntries));

}

// Do the recursive magic (returns a List of strings, each of which is a combination)

return recursiveAppend(0, groupList);

}

// Called by SQL Server for each member of the List of strings

public static void FillRow(object obj, out SqlString combination)

{

// Remove the final comma and return the combination string as a new row

string output = (string)obj;

output = output.Substring(0, output.Length - 1);

combination = new SqlString(output);

}

// The magic

static List<string> recursiveAppend(int level, List<string[]> inputList)

{

List<string> toReturn = new List<string>();

if (level == inputList.Count)

{

toReturn.Add(String.Empty);

return toReturn;

}

foreach (string item in inputList[level])

{

foreach (string partialList in recursiveAppend(level + 1, inputList))

{

if (!partialList.Contains(item + ','))

{

toReturn.Add(item + "," + partialList);

}

}

}

return toReturn;

}

}