数据表未使用最新数据更新

Question

I have a windows form with a combo box that allows a user to select from the drop down list then press a button, which will query an API then populate a SQL Server Table with data, then format the data and display 3 fields on a datagridview. Then the user has the option to discard the data or to export to a csv.

Well this process works perfect for one run, but once you attempt to export a second set of information to a csv the C# variables/datatable retains the information from the first run. (I have verified server side everything is populated as it should be)

I step through my code and debug and have isolated the issue down to the fact that this line of code Form1.dtEmpNames = Form1.allEmps.DefaultView.ToTable(true, "Name"); never updates to the new name that is selected. It keeps the first name.

namespace Be1ng
{
    public partial class Form1 : Form
    {   
        public static DataTable allEmps = new DataTable();
        public static DataTable dtEmpNames = new DataTable();

        public void btnPush_Click()
        {
            allEmps.Clear();

            string query = "Select * from test";
            SqlConnection conn = new SqlConnection(@"Data Source=Server info;Initial Catalog=DB;User Id=user;Password=pwd;");
            conn.Open();
            SqlCommand cmd = new SqlCommand(query, conn);
            SqlDataAdapter sda = new SqlDataAdapter(cmd);
            sda.Fill(allEmps);
            conn.Close();
            Form2 f2 = new Form2();
            f2.ShowDialog();
        }
    }
}
namespace Be1ng
{
    public partial class Form2 : Form
    {
        Private void Form2_Load(object sender, EventArgs e)
        {
            Form1.dtEmpNames = Form1.allEmps.DefaultView.ToTable(true, "Name");
        }
    }
}

Answer 1

Away from the computer so this is untested, and use more meaningful DataTable names, but this should at least provide an example of doing such...

//Form1 - declare the DataTable in the method and pass it to Form2 load
public void btnPush_Click()
{
  DataTable allEmps = new DataTable();
  //Query your server here
  conn.Close();

  //pass the datatable in the call for the form
  Form2 f2 = new Form2(allEmps);
  f2.ShowDialog();
}

//Then in the form2 load create a new constructor that accepts the DataTable
    private DataTable dtpassed = new DataTable();
    private DataTable dtallemps = new DataTable();

    public Form2(DataTable allemps)
    {
        dtallemps = dtpassed;
        InitializeComponent();
    }
    private void Form2_Load(object sender, EventArgs e)
    {
       dtallemps = dtpassed.DefaultView.ToTable(true, "Name");
    }