Question

there is the code for loading image from database and shows it in picture box. the problem is if there’s no pic in a row it will encounter an error however i marked as allow nulls image column in database.

private void button1_Click(object sender, EventArgs e)
{
    sql = new SqlConnection(@"Data Source=PC-PC\PC;Initial Catalog=Test;Integrated Security=True");
    cmd = new SqlCommand();
    cmd.Connection = sql;
    cmd.CommandText = ("select Image from Entry where EntryID =@EntryID");
    cmd.Parameters.AddWithValue("@EntryID", Convert.ToInt32(textBox1.Text));
    var da = new SqlDataAdapter(cmd);
    var ds = new DataSet();
    da.Fill(ds, "Images");
    int count = ds.Tables["Images"].Rows.Count;

    if (count > 0)
    { 
    var data = (Byte[])(ds.Tables["Images"].Rows[count - 1]["Image"]);
    var stream = new MemoryStream(data);
    pictureBox1.Image= Image.FromStream(sream);
    } 
}

Answer 1

you should check for DbNull.Value.

This should do the trick:

if (count > 0)
{ 
       if (ds.Tables["Images"].Rows[count - 1]["Image"] != DbNull.Value){
          var data = (Byte[])(ds.Tables["Images"].Rows[count - 1]["Image"]);
          (MemoryStreamstream = new MemoryStream(data)
           pictureBox1.Image= Image.FromStream(sream);
       }
 } 

You marked column id DB to accept null value so DB handles it but you also need do handle null in your application (you cannot cast DbNull value).

Hint

While using any kind of Stream you should use Using statement to dispose Stream after usage.