using System;

using System.Data;

public class Program

{

    public static void Main()

    {

        var sampleTable = new DataTable("Sample");

        sampleTable.Columns.Add("DateTimeType", typeof(DateTime));

        sampleTable.Columns.Add("StringType", typeof(DateTime));

        sampleTable.Rows.Add(DateTime.Now, DateTime.Now.ToString());

        sampleTable.Rows.Add(null, null);

        foreach (DataRow row in sampleTable.Rows)

        {

            Console.WriteLine($"Row values - DateTimeType: {(row["DateTimeType"] as DateTime?):d}, StringType: {(row["StringType"] as DateTime?):d}");

        }

    }

}