Question

I guess I need to write code in this button click event to get my desired output, but unable write down the steps. Any help from you guys would be helpful and will make me learn. Thank you.

 private void btnViewAllEntries_Click(object sender, EventArgs e)

    {
        SqlConnection con = new SqlConnection(Helper.ConnectionString);
        SqlCommand cmd = new SqlCommand("Select * from DirDetails");
        con.Open();


        con.Close();
        MessageBox.Show(DetailsView.cs);//DetailsView.cs is winform with gridview
    }

Answer 1

First of all, MessageBox just shows messages, not Forms.
To show a Form you should instantiate it and use Show or ShowDialog methods.

DetailsView frm=new DetailsView();
frm.ShowDialog();

Second, run the query in the DetailsView.cs

private void Form1_Load(object sender, EventArgs e)
    {
        SqlConnection con = new SqlConnection(Helper.ConnectionString);
        SqlDataAdapter da = new SqlDataAdapter("Select * from DirDetails", con);
        DataTable dt = new DataTable();
        con.Open();
        da.Fill(dt);
        con.Close();
        datagridview1.DataSource = dt;
    }