gridview With Images的下拉列表

请帮我解决我的问题。我想检索我的图像在gridview中存储在数据库中的图像数据类型。我是新手，请帮帮我。

SqlConnection conn;
SqlCommand cmd;
SqlDataAdapter adp;
string str;
string strCon = "Data Source=S-PC;Initial Catalog=SA;Integrated Security=True";
protected void DropDownList1_SelectedIndexChanged(object sender, EventArgs e)
{
    conn.Open();
    str = "SELECT imgg from SA_Stock where '"+DropDownList1.SelectedItem.Text+"";
    conn = new SqlConnection(strCon);
    cmd=new SqlCommand(str,conn);
    adp=new SqlDataAdapter(cmd);
    DataSet ds = new DataSet();
    adp.Fill(ds);
    GridView1.DataSource = ds.Tables["SA_Stock"];
    GridView1.DataBind();
    conn.Close();
}

提前感谢您的帮助