Use
GridView.DataBind Method [
^]
Try this:
public void gvip()
{
DataTable dt = new DataTable();
conn.Open();
MySqlDataAdapter da;
da = new MySqlDataAdapter("SELECT Reg_No,Reg_Date, Patient_Name, Contact_No, Advance_Amt, Date FROM In_Patients where Delete_Flag='N' ORDER BY Reg_Date DESC", conn);
da.Fill(dt);
conn.Close();
GridView1.DataSource = dt.DefaultView;
GridView1.DataBind();
}