DataRow Comparer == Solution for sorting rows with your own comparer. Helps with customizing the comparison function. Helps the C# Sort() match the ORDER BY in SQL. http://msmvps.com/blogs/deborahk/archive/2009/07/23/linq-sorting-a-datatable.aspx http://stackoverflow.com/questions/3808158/string-comparison-differences-between-net-and-t-sql

datarow-comparer.cs

public class RowComparer : IComparer<System.Data.DataRow> 
{
	public Dictionary<int, bool> SortColumns { get; set; }

	public int Compare(System.Data.DataRow x, System.Data.DataRow y) 
	{
		foreach (int key in SortColumns.Keys) 
		{
			int compareResult;

			if (x.ItemArray[key] == DBNull.Value && y.ItemArray[key] == DBNull.Value)
				compareResult = 0; 
			else if (x.ItemArray[key] == DBNull.Value)
				compareResult = -1; 
			else if (y.ItemArray[key] == DBNull.Value)
				compareResult = 1; 
			else if (x.Table.Columns[key].DataType.Name == typeof(Decimal).Name)
				compareResult = DefaultCompare<decimal>(x.ItemArray[key], y.ItemArray[key]);
			else if (x.Table.Columns[key].DataType.Name == typeof(DateTime).Name)
				compareResult = DefaultCompare<DateTime>(x.ItemArray[key], y.ItemArray[key]);
			else if (x.Table.Columns[key].DataType.Name == typeof(string).Name)
				compareResult =  String.Compare(x.ItemArray[key].ToString(),
								y.ItemArray[key].ToString(),
								System.Globalization.CultureInfo.CurrentCulture,
								System.Globalization.CompareOptions.OrdinalIgnoreCase);
			else if (x.Table.Columns[key].DataType.Name == typeof(bool).Name)
				compareResult = DefaultCompare<bool>(x.ItemArray[key], y.ItemArray[key]);
			else
			{
				switch(x.Table.Columns[key].DataType.Name.ToUpper())
				{
					case "INT16":
						compareResult = DefaultCompare<Int16>(x.ItemArray[key], y.ItemArray[key]);
						break;
					case "Int32":
						compareResult = DefaultCompare<Int32>(x.ItemArray[key], y.ItemArray[key]);
						break;
					case "INT64":
						compareResult = DefaultCompare<Int64>(x.ItemArray[key], y.ItemArray[key]);
						break;
					case "UINT16":
						compareResult = DefaultCompare<UInt16>(x.ItemArray[key], y.ItemArray[key]);
						break;
					case "UINT32":
						compareResult = DefaultCompare<UInt32>(x.ItemArray[key], y.ItemArray[key]);
						break;
					case "UINT64":
						compareResult = DefaultCompare<UInt64>(x.ItemArray[key], y.ItemArray[key]);
						break;
					case "DOUBLE":
						compareResult = DefaultCompare<double>(x.ItemArray[key], y.ItemArray[key]);
						break;
					default:
						throw new ApplicationException(string.Format("Type [{0}] does not have a comparer.", x.Table.Columns[key].DataType.Name));
				}
				
			}

			if (compareResult != 0) 
				return SortColumns[key] ? compareResult: -compareResult; 
		}
		return 0; 
	}
	
	private int DefaultCompare<T>(object a, object b)
	{
		return Comparer<T>.Default.Compare((T) a, (T) b);
	}
}

TODO:

• Convert to using Expressions/ExpressionTrees to speed up comparison