Retrieving image from sql database

Previously i had problem with inserting image into sql database. Now i have solved this problem and able to insert image in sqldatabase. Now I am facing problem with retrieving the image from database table. Here is my retrieving code:

showimage.ashx:
<%@ WebHandler Language="C#" Class="ShowImage" %>
using System;
using System.Web;
using System.IO;
using System.Configuration;
using System.Data.SqlClient;
using System.Data;

public class ShowImage : IHttpHandler 
{

    public void ProcessRequest (HttpContext context)
    {
        int empno;
        if (context.Request.QueryString["empid"] != null)
            empno = Convert.ToInt32(context.Request.QueryString["id"]);
        else
            throw new ArgumentException("No parameter specified");
        context.Response.ContentType = "image/jpeg";
        //context.Response.Write("Hello World");
        Stream strm = ShowEmpImage(empno);
        byte[] buffer = new byte[4096];
        int byteSeq = strm.Read(buffer, 0, 4096);
        while (byteSeq > 0)
        {
            context.Response.OutputStream.Write(buffer, 0, byteSeq);
            byteSeq = strm.Read(buffer, 0, 4096);        
        }        
    }
    public Stream ShowEmpImage(int empno)
    {
        string conn = ConfigurationManager.ConnectionStrings["EmployeeConnString"].ConnectionString;
        SqlConnection connection = new SqlConnection(conn);
        string sql = "SELECT empimg FROM EmpDetails WHERE empid = @ID";
        SqlCommand cmd = new SqlCommand(sql, connection);
        cmd.CommandType = CommandType.Text;
        cmd.Parameters.AddWithValue("@ID", empno);
        connection.Open();
        object img = cmd.ExecuteScalar();
        try
        {
            return new MemoryStream((byte[])img);

        }
        catch
        {
            return null;

        }
        finally
        {
            connection.Close();
        }  
    } 
    public bool IsReusable 
    {
        get
        {
            return false;
        }
    }

}

In this line:

**context.Response.ContentType = "image/jpeg";**

getting exception "No parameter specified"

Pls help me how can i retrieve image from database table. Here is my GUI:

<asp:Label ID="lblEmpName" runat="server" Text="Employee Name"></asp:Label>
&nbsp;&nbsp;&nbsp;&nbsp;
        <asp:TextBox ID="txtEName" runat="server"></asp:TextB开发者_运维知识库ox>
        <br />
        <asp:Label ID="lblImage" runat="server" Text="Employee Image"></asp:Label>
&nbsp;&nbsp;&nbsp;&nbsp;
        <asp:FileUpload ID="imgUpload" runat="server" />
        <br />
        <br />
        <asp:Button ID="btnSubmit" runat="server" Text="Submit" 
            onclick="btnSubmit_Click" />   
    &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp      
     <asp:Label ID="lblResult" runat="server" ForeColor="#0066FF"></asp:Label>
    <br />
    <hr />  
   <asp:Image ID="Image1" style="width:200px" Runat="server"/>   

The exception you are seeing is actually the one thrown on the line above:

throw new ArgumentException("No parameter specified");

I.e. caused because your request does not have the empid query string:

somepage.aspx?empid=42

Other than that I cant see anything else obviously wrong in your code.

The error message you are getting, looks like is due to empid being missing as Kragen points out.

I think that you could simplify your code a great deal:

• You have an object that you cast to a byte array
• You then use the byte array to create a stream
• You then convert the stream to a byte array.

Why not just return the byte array?

This link may also help you: http://www.worldofasp.net/tut/images/Displaying_images_in_ASPNET_using_HttpHandlers_92.aspx