Ładowanie obrazu PictureBox z bazy danych

Kontynuuj coś takiego w button1_Click:

// Your code first, here.

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(stream);
}