How Do I Call Method Repeatedly after specific Time Interval In Tick Event Of Timer?

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C#

C#4.0

I have 1 method for importing files from folder but i don't have all files in that folder the files are coming from ftp to that folder.and i have table with 1 field as primary key , when i run program files successfully imported in database which are present at the time of execution of program but when new files are coming into folder from server those files not imported in database. and at all interval error comes "Violation of primary key constraint" but i can't remove primary key otherwise duplicate files saved again and again.
Help me to solve this problem.


Here is my code

namespace Module1 
{
 public partial class DeviceDetails : Form 
{
 //Timer initialises// System.Windows.Forms Timer t = new System.Windows.Forms Timer();

    public DeviceDetails()
    {
        InitializeComponent();
      //  ImportAllFilesOfFolder();
    }

    //Initialize data connection componants//
    SqlConnection con = new SqlConnection(----some conn string----);
    DataTable dt;
    SqlDataAdapter dataAdap;
    SqlCommandBuilder scmd;

    private void DeviceDetails_Load_1(object sender, EventArgs e)
    {
                  this.deviceDetailsTableAdapter.Fill(this.hospitalProjectDataSet.DeviceDetails);

        t.Interval = 100000;  // interval in millisecond
        t.Tick += new EventEventHandler(t_Tick);           
        t.Enabled = true;
        t.Start();
    }

     void t_Tick(object sender, EventArgs e)
    { 
        GetData("select from DeviceDetails.csv");
        ImportAllFilesOfFolder();         
    }

Here is import method

public void ImportAllFilesOfFolder() { try { SqlConnection con = new SqlConnection(----con string----); string sourceDir = @"---folder path to import from---"; var IcsvFile = Directory.EnumerateFiles(sourceDir, "*.csv");

            foreach (string currentFile in IcsvFile)
            {                   
                    StreamReader sr = new StreamReader(currentFile);
                    string line = sr.ReadLine();
                    string[] value = line.Split(',');
                    DataTable dt = new DataTable();
                    DataRow row;

                    foreach (string dc in value)
                    {
                        dt.Columns.Add(new DataColumn(dc));
                    }

                    while (!sr.EndOfStream)
                    {
                        value = sr.ReadLine().Split(',');
                        if (value.Length == dt.Columns.Count)
                        {
                            row = dt.NewRow();
                            row.ItemArray = value;
                            dt.Rows.Add(row);
                        }
                    }

                    SqlBulkCopy bc = new SqlBulkCopy(con.ConnectionString, SqlBulkCopyOptions.TableLock);
                    bc.DestinationTableName = "DeviceDetails";
                    bc.BatchSize = dt.Rows.Count;
                    con.Open();
                    bc.WriteToServer(dt);
                    bc.Close();
                    con.Close();
                }
            }

[edit]Code block added - OriginalGriff[/edit]