Disable Button after download using C# and VB.Net in ASP.Net

Hi suhaas121,

I have created a sample please take its refrence and correct your code.

Database

This article makes use of a table named tblFiles whose schema is defined as follows.

You can download the database table SQL by clicking the download link below.

Download SQL file

HTML

ID:<asp:TextBox runat="server" ID="txtID" />
<asp:Button ID="btndownload" runat="server" Text="Download" OnClick="btndownload_Click"
    Style="font-weight: bold;" OnClientClick="this.disabled = true;" UseSubmitBehavior="false" />

Namespaces

C#

using System.Configuration;
using System.Data.SqlClient;

VB.Net

Imports System.Configuration
Imports System.Data.SqlClient

Code

C#

protected void btndownload_Click(object sender, EventArgs e)
{
    SqlConnection conn = new SqlConnection(ConfigurationManager.ConnectionStrings["conString"].ConnectionString);
    try
    {
        byte[] bytes;
        btndownload.Enabled = false;
        string filename, contentType;
        SqlCommand cmd1 = new SqlCommand("SELECT Name, Data, ContentType FROM TblFiles WHERE ID=@ID", conn);
        cmd1.Parameters.AddWithValue("@ID", txtID.Text.Trim());
        conn.Open();
        SqlDataReader dr = cmd1.ExecuteReader();
        if (dr.Read())
        {
            btndownload.Enabled = false;
            bytes = (byte[])dr["Data"];
            contentType = dr["ContentType"].ToString();
            filename = dr["Name"].ToString();
            conn.Close();
            Response.Clear();
            Response.Buffer = true;
            Response.Charset = "";
            Response.Cache.SetCacheability(HttpCacheability.NoCache);
            Response.ContentType = contentType;
            Response.AppendHeader("Content-Disposition", "attachment; filename=" + filename);
            Response.BinaryWrite(bytes);
            Response.Flush();
            Response.End;
        }        
    }
    catch (Exception ex)
    {
    }
}

VB.Net

Protected Sub btndownload_Click(ByVal sender As Object, ByVal e As EventArgs)
    Dim conn As SqlConnection = New SqlConnection(ConfigurationManager.ConnectionStrings("conString").ConnectionString)
    Try
        Dim bytes As Byte()
        btndownload.Enabled = False
        Dim filename, contentType As String
        Dim cmd1 As SqlCommand = New SqlCommand("SELECT Name, Data, ContentType FROM TblFiles WHERE ID=@ID", conn)
        cmd1.Parameters.AddWithValue("@ID", txtID.Text.Trim())
        conn.Open()
        Dim dr As SqlDataReader = cmd1.ExecuteReader()
        If dr.Read() Then
            btndownload.Enabled = False
            bytes = CType(dr("Data"), Byte())
            contentType = dr("ContentType").ToString()
            filename = dr("Name").ToString()
            conn.Close()
            Response.Clear()
            Response.Buffer = True
            Response.Charset = ""
            Response.Cache.SetCacheability(HttpCacheability.NoCache)
            Response.ContentType = contentType
            Response.AppendHeader("Content-Disposition", "attachment; filename=" & filename)
            Response.BinaryWrite(bytes)
            Response.Flush()
            Response.End()
        End If
    Catch ex As Exception
    End Try
End Sub

Screenshot