C#

For Each dr As DataRow In sourceTable.Rows
    destinationTable.ImportRow(dr)
Next

DataTable b, a;
 foreach (DataRow dr in a.Rows)
 {
     string id = dr["id"].ToString(); /// "id" is the primary key
     DataRow[] bDr = b.Select(string.Format("id = '{0}'", id));
     bDr[0]["value"] = dr["value"];   // value is the new column you want to add
 }

jon_80 wrote:

does not allow me to call the ArithmeticUtilityException.Divide() method. Why?

public class ArithmeticUtilityException : ApplicationException
{
    public ArithmeticUtilityException() : base() {}
    public ArithmeticUtilityException(string message) : base(message) {}
    public ArithmeticUtilityException(string message, Exception inner) : base(message, inner) {}
}

public static class ArithmethicUtility
{
    public decimal Divide(decimal number, decimal divisor)
    {
    ...
    }
}

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using CustomException;

namespace CustomException
{
    class Program
    {
        static void Main(string[] args)
        {
            ArithmethicUtility utility = new ArithmethicUtility();
            Decimal myNumber = utility.Divide(5, 0);
        }
    }

    public class ArithmeticUtilityException : ApplicationException
    { 
        public ArithmeticUtilityException() : base() {}
        public ArithmeticUtilityException(string message) : base(message) {}
        public ArithmeticUtilityException(string message, Exception inner) : base(message, inner) {}
    }

    public class ArithmethicUtility
    {
        public decimal Divide(decimal number, decimal divisor)
        {
            try
            { return number / divisor; }
            catch (Exception err)
            {
                /*  
                 * Create an instance of the specialized exception class, and, 
                 * place the original error in the InnerException property. 
                 */
                ArithmeticUtilityException errNew = new ArithmeticUtilityException("Divide by zero", err);
                throw errNew;
            }
        }
    }
}

public class Employee
{
    private string name;
    private List<Manager> managers;

    public string Name
    {
        get { return name; }
        set { name = value; }
    }

    public List<Manager> Managers
    {
        get
        {
            if(managers == null)
                return new List<Manager>();
            return managers;
        }
        set { managers = value; }
    }
}