How to hide image field if there is no image in database ASP.NET

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I have 2 questions.

First problem. When i have uploaded image in my database for specific user than my program working good and i successful log in , but if i dont have uploaded image i got this exception. [^]

And second question. How can i make it to hide image field if there is no image in specific column in database.
For example if i have 3 image fields in database and on my profile.aspx and only 1 image is uploaded , how i can hide other 2.
I hope you understand my concern(my english is not perfect).

What I have tried:

This is my code:
public partial class Control_Panel : System.Web.UI.Page
{
SqlCommand cmd = new SqlCommand();
SqlConnection con = new SqlConnection();
SqlDataAdapter sda = new SqlDataAdapter();
DataSet ds = new DataSet();
protected void Page_Load(object sender, EventArgs e)
{
if(Session["User"] == null )
{
Response.Redirect("Login.aspx");
}
else
{
con.ConnectionString = "Data Source=JOSIPPC\\SQLEXPRESS;Initial Catalog=register;Integrated Security=True";
con.Open();
showdata();

}
}

protected void Button1_Click(object sender, EventArgs e)
{
Session["user"] = null;
Response.Redirect("Login.aspx");
}
public void showdata()
{
cmd.CommandText = "Select* from Table_1 where Email_id = '" +Session["user"]+ "'";
cmd.Connection = con;
sda.SelectCommand = cmd;
sda.Fill(ds);
Label1.Text = ds.Tables[0].Rows[0]["First_Name"].ToString() + " "+ ds.Tables[0].Rows[0]["Last_Name"].ToString();
Label2.Text = ds.Tables[0].Rows[0]["Email_id"].ToString();

cmd.CommandText = "select Images from Table_1 where Email_id='" + Session["user"] + "'";
cmd.Connection = con;
SqlDataReader dr = cmd.ExecuteReader();
if (dr.HasRows)
{
while (dr.Read())
{

byte[] imgd = (byte[])dr["Images"];
string images = Convert.ToBase64String(imgd, 0, imgd.Length);
Image1.ImageUrl = "data:image/png;base64," + images;

}
}
else
{
}
}
}

Posted 22-Jan-18 7:20am

Gatsby29

Updated 22-Jan-18 7:31am

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Comments

Richard Deeming 23-Jan-18 12:39pm

Your code is vulnerable to SQL Injection[^]. NEVER use string concatenation to build a SQL query. ALWAYS use a parameterized query.

Everything you wanted to know about SQL injection (but were afraid to ask) | Troy Hunt[^]
How can I explain SQL injection without technical jargon? | Information Security Stack Exchange[^]
Query Parameterization Cheat Sheet | OWASP[^]

using (var con = new SqlConnection("Data Source=JOSIPPC\\SQLEXPRESS;Initial Catalog=register;Integrated Security=True"))
using (var cmd = new SqlCommand("Select First_Name, Last_Name, Email_Id, Images from Table_1 where Email_id = @user", con))
{
    cmd.Parameters.AddWithValue("@user", Session["user"]);
    
    con.Open();
    
    using (var reader = cmd.ExecuteReader())
    {
        if (reader.Read())
        {
            Label1.Text = string.Format("{0} {1}", reader["First_Name"], reader["Last_Name"]);
            Label2.Text = reader["Email_Id"].ToString();
            
            object img = reader["Images"];
            if (img != null && !Convert.IsDBNull(img))
            {
                ...
            }
        }
    }
}

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Karthik_Mahalingam · Accepted Answer · 2018-01-22T07:31:00

based on the screenshot, you are trying to cast the DBNUll Value to byte array, Validate for null and DbNull value before casting the object

Image1.Visible = false;
            object img = dr["Images"];
            if (img != null && img != DBNull.Value)
            {
                Image1.Visible = true;
                byte[] imgd = (byte[])dr["Images"];
                string images = Convert.ToBase64String(imgd, 0, imgd.Length);
                Image1.ImageUrl = "data:image/png;base64," + images;
            }