LINQ: Add RowNumber Column

Question

How can the query below be modified to include a column for row number (ie: one-based index of results)?

var myResult = from currRow in someTable
                    


        

Answer 1

Use this Select method:

Projects each element of a sequence into a new form by incorporating the element's index.

Example:

var myResult = someTable.Where(currRow => currRow.someCategory == someCategoryValue)
                        .OrderByDescending(currRow => currRow.createdDate)
                        .Select((currRow, index) => new {Row = currRow, Index = index + 1});

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In response to your edit:

If you want a DataTable as result, you can go the non-Linq way by simply using a DataView and add a additional column afterwards.

someTable.DefaultView.RowFilter = String.Format("someCategory = '{0}'", someCategoryValue);
someTable.DefaultView.Sort = "createdDate";
var resultTable = someTable.DefaultView.ToTable();
resultTable.Columns.Add("Number", typeof(int));
int i = 0;
foreach (DataRow row in resultTable.Rows)
    row["Number"] = ++i;