.net修改 image代码错误，请教

Question

我用asp.net修改sqlserver的image字段内容，请问哪里不对？str="update db set attach=@attach where id=1"
dim cm as sqlcommand(str,cn)
cm.parameters.add("@attach",imadata)
try
  cn.open
  cm.executenonquery()
catchfinally
   cn.close
end try

Answer 1

给你一段示例,参考对照一下,应该对你有帮助的
页面类代码:protected void Button1_Click(object sender, EventArgs e)
    {
        Guanggao gg = new Guanggao();
        ImgManager im = new ImgManager();
        if (this.FileUpload1.FileName != "")
        {
            gg.Img1 = "centenimg";
            gg.Img2 = this.FileUpload1.FileName.Trim();
            int count = im.Imginfo(gg);
            if (count >= 0)
            {
                string spath = Server.MapPath("~/images/");
                this.FileUpload1.SaveAs(spath + this.FileUpload1.FileName);
                Response.Redirect("Default.aspx", false);            }
            else
            {
                Response.Write("<script>alert('添加失败！！');</script>");
            }
        }
        else
        {
            Response.Write("<script>alert('确认更新?????');</script>");
        }
    }业务层代码:namespace NewsBLL
{
    public class ImgManager
    {
        ImgService ims = new ImgService();
        public int Imginfo(Guanggao g)
        {
            return ims.Imginsert(g);
        }
        public Guanggao GetImage(string name)
        {
            return ims.GetImg(name);
        }
    }
}数据层代码:namespace NewsDAL
{
    public class ImgService
    {
        public int Imginsert(Guanggao g)
        {
            string sql = "insert into Images values(@name,@image)";
            SqlParameter[] spm = new SqlParameter[]
            {
                new SqlParameter("@name",g.Img1),
                new SqlParameter("@image",g.Img2)
            };
            int count = DBHelper.GetScalar(sql, spm);
            return count;
        }
        public Guanggao GetImg(string name)
        {
            string sql = "select Image from Images where IName='" + name + "'";
            Guanggao gg = new Guanggao();
            using (SqlDataReader dr = DBHelper.GetReader(sql))
            {
                while (dr.Read())
                {                    gg.Img2 = Convert.ToString(dr["Image"]);
                }
            }
            return gg;
        }
    }
    
}调用的连接代码: public static class DBHelper
    {
        //数据库连接属性
        private static SqlConnection connection;
        public static SqlConnection Connection
        {
            get
            {
                string connectionString = ConfigurationManager.ConnectionStrings["NewsConnectionString"].ConnectionString;
                if (connection == null)
                {
                    connection = new SqlConnection(connectionString);
                    connection.Open();
                }
                else if (connection.State == System.Data.ConnectionState.Closed)
                {
                    connection.Open();
                }
                else if (connection.State == System.Data.ConnectionState.Broken)
                {
                    connection.Close();
                    connection.Open();
                }
                return connection;
            }
        }
/// <summary>
        /// 执行无参SQL语句，并返回执行记录数
        /// </summary>
        public static int GetScalar(string safeSql)
        {
            SqlCommand cmd = new SqlCommand(safeSql, Connection);
            int result = Convert.ToInt32(cmd.ExecuteScalar());
            return result;
        }
        /// <summary>
        /// 执行有参SQL语句，并返回执行记录数
        /// </summary>
        public static int GetScalar(string sql, params SqlParameter[] values)
        {
            SqlCommand cmd = new SqlCommand(sql, Connection);
            cmd.Parameters.AddRange(values);
            int result = Convert.ToInt32(cmd.ExecuteScalar());
            return result;
        }
        /// <summary>
        /// 执行无参SQL语句，并返回SqlDataReader
        /// </summary>
        public static SqlDataReader GetReader(string safeSql)
        {
            SqlCommand cmd = new SqlCommand(safeSql, Connection);
            SqlDataReader reader = cmd.ExecuteReader();
            return reader;
        }
        /// <summary>
        /// 执行有参SQL语句，并返回SqlDataReader
        /// </summary>
        public static SqlDataReader GetReader(string sql, params SqlParameter[] values)
        {
            SqlCommand cmd = new SqlCommand(sql, Connection);
            cmd.Parameters.AddRange(values);
            SqlDataReader reader = cmd.ExecuteReader();
            return reader;
        }

Answer 2

imadata 必须为 byte[] 类型才可以。
查考我的文章，上面写的很明白：
http://www.cnblogs.com/wfyfngu/archive/2008/10/09/1307390.html

Answer 3

谢谢高手指点！我的上传照片代码运行正常，update语句不知错在哪里？