DataGridView not showing data when i use while loop or if statement

Question

private void button1_Click(object sender, EventArgs e)
    {
        try
        {
            SqlCommand cmd = new SqlCommand("select * from AccountTbl where EmployeeCode=" + comboBox1.Text, con);
            con.Open();
            DataTable dt = new DataTable();
            SqlDataReader dr = cmd.ExecuteReader();
            while (dr.Read())
            {
                textBox1.Text = (dr["Status"].ToString());
            }
            dt.Load(dr);
            dataGridView1.DataSource = dt;
            con.Close();

        }
        catch (Exception ex)
        {

            MessageBox.Show("Enter");
        }
        finally
        {
            con.Close();
        }
    }

Answer 1

So when debugging your snippet, you should be able to see, that there is data read by the dr.Read().

And while reading your DataReader dr.Read() will consume all incoming data rows one-by-one. And within your while-loop you will operate with the received data.

// Get data row by row
while (dr.Read())
{
     // Displays the current "Status" content in your textbox
     textBox1.Text = (dr["Status"].ToString());
}

And when it now comes to creating your DataTable with Load(). The reader has just finished reading and hasn't any row left to read.

dt.Load(dr);

So your displayed DataGrid will be empty.

---

As a hint:
I recommend wrapping your data reader in a using block like

using(SqlDataReader dr = cmd.ExecuteReader())
{
   while (dr.Read())
   {
      //Processing
   }

   // or

   dt.Load(dr);
}

This will close and dispose your data reader. You may take a look at Is it necessary to manually close and dispose of SqlDataReader?