MySQL Data Synchronisation from different Databases in C#
using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Linq;
using System.Text;
using System.Windows.Forms;
using MySql.Data.MySqlClient; 

namespace DBsync2
{
      //table2 is the Master(with duplicates) Table and table1 is the one without duplicates 

&lt;pre&gt;
public partial class Form1 : Form
{
    private MySqlConnection conn1 = null;
    private MySqlConnection conn2 = null;
    string cs1,cs2;

    class IdTsEntry
    {
        public Int64 fid { get; set; }
        public String fdate { get; set; }
    }

    void Init()
    {
        //initialize cs1, cs2 to suit the database connection details.

        try
        {
            string servername1 = server1.ToString();
            string uname1 = uid1.ToString();
            string pass1 = pwd1.ToString();
            string dbName1 = dbname1.ToString();

            string tbl1 = table1.ToString();
            string tbl2 = table2.ToString();

            conn1 = new MySqlConnection(cs1);
            conn1.Open();
            conn2 = new MySqlConnection(cs2);
            conn2.Open();

            tbl1 = "abc";
            tbl2 = "def";

            // Load target list's ids and timestamps
            string stmt1 = "SELECT seriennummer, DATE_FORMAT(fdate, '%Y-%M-%D %H:%i:%s') FROM " + tbl1;
            MySqlCommand cmd1 = new MySqlCommand(stmt1, conn1);
            List&amp;lt;IdTsEntry&amp;gt; A = new List&amp;lt;IdTsEntry&amp;gt;();
            using (MySqlDataReader reader = cmd1.ExecuteReader())
            {
                //while (reader.Read())
                //{ // I assume the fields are set to NOT NULL
                //    A.Add(new IdTsEntry()
                //    {
                //        fid = reader.GetInt64(0),
                //        fdate = reader.GetString(1)
                //    });
                //}

                while (reader.Read())
                { // I assume the fields are set to NOT NULL
                    A.Add(new IdTsEntry()
                    {
                        fid = reader.IsDBNull(0) ? -1L : reader.GetInt64(0),
                        fdate = reader.IsDBNull(1) ? "" : reader.GetString(1)
                    });
                }
            }
            // Load source list's ids and timestamps
            string stmt2 = "SELECT fid, DATE_FORMAT(fdate, '%Y-%M-%D %H:%i:%s') FROM " + tbl2;
            MySqlCommand cmd2 = new MySqlCommand(stmt2, conn2);

            List&amp;lt;IdTsEntry&amp;gt; B = new List&amp;lt;IdTsEntry&amp;gt;();
            using (MySqlDataReader reader = cmd2.ExecuteReader())
            {
                while (reader.Read())
                { // I assume the fields are set to NOT NULL
                    B.Add(new IdTsEntry()
                    {
                        fid = reader.GetInt64(0),
                        fdate = reader.GetString(1)
                    });
                }

            }

            // Filter lists
            List&amp;lt;Int64&amp;gt; List1 = new List&amp;lt;Int64&amp;gt;();
            List&amp;lt;Int64&amp;gt; List2 = new List&amp;lt;Int64&amp;gt;();
            foreach (IdTsEntry b in B)
            {
                var a = A.FirstOrDefault(e =&amp;gt; e.fid.Equals(b.fid));
                if (a == null) 
                    List2.Add(b.fid); // b.id not in A -&amp;amp;gt; new row
                else if (!a.fdate.Equals(b.fdate))
                    List1.Add(b.fid); // b.id in A but other timestamp -&amp;amp;gt; altered row
            }

                        // Update altered rows
            //string ct1 = "SELECT variante,charge,DATE_FORMAT(fdate, '%Y-%M-%D %H:%i:%s') FROM " + tbl2 + " WHERE fid = {0}";
            //string ct2 = "UPDATE " + tbl1 + " SET variante = @val1,charge = @val2, fdate = @val3 WHERE seriennummer = {0}";
            foreach (Int64 id in List1)
            {
                // Read all entry values into parameters
               // cmd1.CommandText = String.Format(ct1, id);
                cmd1.CommandText = "SELECT variante,charge,DATE_FORMAT(fdate, '%Y-%M-%D %H:%i:%s') FROM " + tbl2 + " WHERE fid = " + id.ToString();

               // MessageBox.Show(cmd1.CommandText);
                cmd2.Parameters.Clear();
                int i = 0;
                using (MySqlDataReader reader = cmd1.ExecuteReader())
                {
                    if (!reader.Read()) continue; 
                    for (int n = 0; n &amp;lt; reader.FieldCount; n++)
                    {
                        cmd2.Parameters.AddWithValue(String.Format("val{0}", ++i),
                            reader.IsDBNull(n) ? DBNull.Value : reader.GetValue(n));
                    }

                }
                // Update row
                //cmd2.CommandText = String.Format(ct2, id);
                cmd2.CommandText = "UPDATE " + tbl1 + " SET variante = @val1,charge = @val2, fdate = @val3 WHERE seriennummer = " + id.ToString();
                cmd2.ExecuteNonQuery();
            }

                            // Insert new rows
            //ct1 = "SELECT fid, variante,charge,DATE_FORMAT(fdate, '%Y-%M-%D %H:%i:%s') FROM " + tbl2 + " WHERE fid = {0}";
            //ct2 = "INSERT INTO " + tbl1 + " (seriennummer, variante,charge,fdate) " +
            //    "VALUES (@val1, @val2, @val3, @val4)";
            //    cmd2.CommandText = ct2;
                cmd2.CommandText = "INSERT INTO " + tbl1 + " (seriennummer,variante,charge,fdate) " +
                    "VALUES (@val1, @val2, @val3, @val4)";
                foreach (Int64 id in List2)
                {
                    // Read all values into parameters
                    //cmd1.CommandText = String.Format(ct1, id);

                    cmd1.CommandText = "SELECT fid,variante,charge,DATE_FORMAT(fdate, '%Y-%M-%D %H:%i:%s') FROM " + tbl2 + " WHERE fid = " + id.ToString();
                    cmd2.Parameters.Clear();
                    int i = 0;
                    using (MySqlDataReader reader = cmd1.ExecuteReader())
                    {
                        if (!reader.Read()) continue;
                        for (int n = 0; n &amp;lt; reader.FieldCount; n++)
                        {
                            cmd2.Parameters.AddWithValue(String.Format("val{0}", ++i),
                                reader.IsDBNull(n) ? DBNull.Value : reader.GetValue(n));
                        }
                    }
                    // Insert row
                    cmd2.ExecuteNonQuery();
                }

        }

        catch (MySqlException ex)
        {
            MessageBox.Show("Error: " + ex.ToString());

        }

    }
    public Form1()
    {
        InitializeComponent();

        Init();

    }

}


}