How to check for null column in a DataRow

Question

I'm using DataTables in 4.7.2, and I have defined a table with 2 columns, Start_Date and End_Date.

If the 2nd column has a null value, how can I check for that? Right now I've gotten this far, which

abends at runtime:

// foreach (DataRow eachrow in myrows)

// {

// if (eachrow.Field<DateTime>("End_Date") == null) process_date = DateTime.Now;

// }

Answer 1

Hi @Coreysan , Welcome to Microsoft Q&A,

Logically there is nothing wrong with your code, but to safely check if eachrow.Field<DateTime>("End_Date") is null, you should use the IsNull method.

I wrote a small example to demonstrate:

using System;
using System.Data;

namespace _9_26_x
{
    internal class Program
    {
        static void Main(string[] args)
        {
            //Create a simple DataTable
            DataTable table = new DataTable();
            table.Columns.Add("Start_Date", typeof(DateTime));
            table.Columns.Add("End_Date", typeof(DateTime));

            //Add some sample data
            table.Rows.Add(DateTime.Parse("2023-09-01"), DateTime.Parse("2023-09-10"));
            table.Rows.Add(DateTime.Parse("2023-09-11"), DBNull.Value); // "End_Date" is null
            table.Rows.Add(DateTime.Parse("2023-09-21"), DateTime.Parse("2023-09-30"));

            DateTime process_date = DateTime.Now; //Default process_date

            // Loop through each row and check "End_Date"
            foreach (DataRow row in table.Rows)
            {
                if (row.IsNull("End_Date"))
                {
                    process_date = DateTime.Now; // Set process_date when "End_Date" is null
                }
                else
                {
                    DateTime endDate = row.Field<DateTime>("End_Date");
                    // "End_Date" is not null, you can use endDate
                    Console.WriteLine("Start Date: " + row.Field<DateTime>("Start_Date"));
                    Console.WriteLine("End Date: " + endDate);
                }
            }

            Console.WriteLine("Process Date: " + process_date);
            Console.ReadLine();
        }
    }
}

Best Regards,

Jiale

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