using (StreamReader sr = new StreamReader("c:\\file.csv", System.Text.Encoding.GetEncoding("iso-8859-1")))
{
int i = 0;
string line;


while ((line = sr.ReadLine()) != null)
{
string[] arrLine = line.Split(delimiterChars);

ID = "";
mitem = "";
V01 = "";

ID = arrLine[0].ToString().Trim();
mitem = arrLine[1].ToString().Trim();
V01 = arrLine[2].ToString().Trim();

sql = @"UPDATE tabella SET v01=@V01 WHERE id=@ID";

cmd = new OleDbCommand(sql, conn);
cmd.Parameters.Add("@V01", OleDbType.VarChar, 30);
cmd.Parameters["@V01"].Value = V01;
cmd.Parameters.Add("@ID", OleDbType.Numeric);
cmd.Parameters["@ID"].Value = ID;

rows = cmd.ExecuteNonQuery();

i++;
}
}