必须声明标量变量“@img”。 C＃

Question

I am making an application which uses Picture and Thumb impression by using picture box and I am getting this error for my code below any help?

con = new SqlConnection(DBHelper.Conectionstring());
con.Open();
cmd = new SqlCommand();
cmd.Parameters.Add("@img",SqlDbType.Image);
cmd.Parameters.Add("@thmb", SqlDbType.Image);
cmd.Connection = con;
MemoryStream ms = new MemoryStream();
MemoryStream ms1 = new MemoryStream();
this.pbxaddpic.Image.Save(ms, this.pbxaddpic.Image.RawFormat);
this.pbxthumb.Image.Save(ms, this.pbxthumb.Image.RawFormat);
byte[] b = ms.GetBuffer();
byte[] t = ms.GetBuffer();
ms.Close();
cmd.Parameters.Clear();
cmd.Parameters.AddWithValue("@img", b);
cmd.Parameters.AddWithValue("@thmb", t);
int maxpartycode = getmaxpartycode();
cmd.CommandText = "insert into tbl_partyinfo values(" + maxpartycode + ",'" + this.txtname.Text
      + "','" + this.txtfathername.Text + "','" + this.txtcnic.Text +"','"+this.txtaddress.Text+ "','"+this.txtcontactno.Text
      + "','" + this.txtbusinessname.Text + "','" + this.txtbusinessaddress.Text +"','"+this.txtemail.Text+"', '"+this.txtfax.Text
      +"',@img,@thmb)";
cmd.ExecuteNonQuery();
con.Close();
cmd = null;
MessageBox.Show("Details Added")

Answer 1

When you do (after ms.Close()):

cmd.Parameters.Clear(); 

it will clear all the parameters from the Parameters collection. So when you try to add the values, the parameter is unavailable hence the error. I don't get why you need to clear the parameters, but if you really need to do that, you will have to add parameter before adding the value. Like

  cmd.Parameters.Add("@img", SqlDbType.Image);
  cmd.Parameters.Add("@thmb", SqlDbType.Image)
  cmd.Parameters.AddWithValue("@img", b);
  cmd.Parameters.AddWithValue("@thmb", t);