C# 在特定位置读取十六进制并返回相应文本

选择图片文件后，程序将运行，通过与提供的数据库进行比较来扫描文件头

然后继续确定图片文件的文件源。问题是，当我使用系统扫描图片文件时，我无法像在页眉上那样找到源

检索具有特定格式的十六进制代码（例如：40 70 6c 65），将其与数据库进行比较，返回“源代码”

private void sourceDatabase(BinaryReader reader)
    {
        byte[] buffer = new byte[5];
        reader.BaseStream.Seek(reader.BaseStream.Length, SeekOrigin.Begin);
        reader.Read(buffer, 0, 5);

        string source = "";
        foreach (var item in buffer)
        {
            string temp = "0";
            if (item.ToString("X").Length == 1)
                source += temp + item.ToString("X") + " ";
            else
                source += item.ToString("X") + " ";
        }
        if (source.Length != 0)
            source = source.Substring(0, source.Length - 1);
        MessageBox.Show("File Source : " + source, "Result");

        SqlConnection connection = new SqlConnection(ConfigurationManager.ConnectionStrings["databaseConnectionString"].ConnectionString);
        connection.Open();
        SqlCommand command = null;
        string ori_source = source;
        //int flag = 1;
        while (true)
        {
            string sql = "SELECT source FROM sourceDatabase WHERE Hexadecimal like '" + source + "%'";
            command = new SqlCommand(sql, connection);
            if (source.Length != 0 && source.Length > 5)
            {
                source = source.Substring(0, source.Length - 1);
                if (command.ExecuteScalar() != null)
                {
                    string scr = System.Convert.ToString(command.ExecuteScalar().ToString());
                    //string desc = command.ExecuteScalar().ToString();
                    MessageBox.Show("Source : " + scr, "Result");
                    //flag = 2;
                    break;
                }
            }
            else break;
        }
    }