using System;
using System.Configuration;
using System.Data;
using System.Linq;
using System.Web;
using System.Web.Security;
using System.Web.UI;
using System.Web.UI.HtmlControls;
using System.Web.UI.WebControls;
using System.Web.UI.WebControls.WebParts;
using System.Xml.Linq;
using System.Data.SqlClient;

public partial class _Default : System.Web.UI.Page 
{
    SqlConnection con;
    SqlCommand cmd;

    public void DataConnection()
    {
        con = new SqlConnection(System.Configuration.ConfigurationManager.AppSettings["RDCConnection"]);
        con.Open();
    }
    protected void Page_Load(object sender, EventArgs e)
    {

    }
    protected void btnSave_Click(object sender, EventArgs e)
    {
        DataConnection();
        cmd = new SqlCommand();
        cmd.CommandText = "Insert into imagetest(imgname)values('" + FileUpload1.FileName + "')";
        cmd.CommandType = CommandType.Text;
        cmd.Connection = con;
        string strPath = Server.MapPath("~/img/");
        if (FileUpload1.HasFile)
        {
            FileUpload1.SaveAs(strPath + FileUpload1.FileName);
        }
        cmd.ExecuteNonQuery();
        
        Response.Write("File save successfully");
    }
  
}

<asp:FileUpload ID="FileUpload1" runat="server" />
<asp:Button ID="btnSave" runat="server" onclick="btnSave_Click" Text="Save" />
<asp:Button ID="Button1" runat="server" onclick="Button1_Click" Text="Button" />