Lập Trình .NET

        public static string ToBase64(this string src, Encoding encoding)
        {
            byte[] b = encoding.GetBytes(src);
            return Convert.ToBase64String(b);
        }

        public static string Base64ToString(this string src, Encoding encoding)
        {
            byte[] b = Convert.FromBase64String(src);
            return encoding.GetString(b);
        }

        public static string RemoveHtml(this string text)
        {
            return Regex.Replace(text, "<[^>]*>", string.Empty);
        }

        public static string HtmlEncode(this string src)
        {
            return System.Net.WebUtility.HtmlEncode(src);
        }

        public static string HtmlDecode(this string src)
        {
            return System.Net.WebUtility.HtmlDecode(src);
        }

        public static string UrlEncode(this string src)
        {
            return System.Web.HttpUtility.UrlEncode(src);
        }

        public static string UrlDecode(this string src)
        {
            return System.Web.HttpUtility.UrlDecode(src);
        }

Using SQL Server Management Studio

Using Transact-SQL

USE master;
GO
ALTER DATABASE AdventureWorks2012
SET SINGLE_USER
WITH ROLLBACK IMMEDIATE;
GO
ALTER DATABASE AdventureWorks2012
SET READ_ONLY;
GO
ALTER DATABASE AdventureWorks2012
SET MULTI_USER;
GO

<configSections>
    <section name="log4net" type="log4net.Config.Log4NetConfigurationSectionHandler, log4net" />
</configSections>
<log4net debug="true">
    <appender name="RollingLogFileAppender" type="log4net.Appender.RollingFileAppender">
      <file value="LogFileName.txt" />
      <appendToFile value="true" />
      <rollingStyle value="Size" />
      <maxSizeRollBackups value="10" />
      <maximumFileSize value="1MB" />
      <staticLogFileName value="true" />
      <layout type="log4net.Layout.PatternLayout">
        <conversionPattern value="%-5p %-8d %rms %-22.22c{1} %-18.18M - %m%n" />
      </layout>
    </appender>
    <root>
      <level value="ALL" />
      <appender-ref ref="RollingLogFileAppender" />
    </root>
</log4net>

protected void Application_Start(object sender, EventArgs e)
{
      log4net.Config.XmlConfigurator.Configure();
}

private static readonly ILog logger = LogManager.GetLogger(System.Reflection.MethodBase.GetCurrentMethod().DeclaringType);

TcpClient client = new TcpClient();

string log = "";

client.Connect("mail.emailserver.vn", 25);
            
StreamReader sr = new StreamReader(client.GetStream());
StreamWriter sw = new StreamWriter(client.GetStream());

log += "Server: " + sr.ReadLine() + "\n";

string data = "HELO";//một vài server yêu cầu phải HELO sender hostname

log += "Client: " + data + "\n";
sw.WriteLine(data);
sw.Flush();

log += "Server: " + sr.ReadLine() + "\n";

//Khai báo địa chỉ người gửi
data = "MAIL FROM: <" + "nguyxxdoxxphoxx.it@gmail.com" + ">";
log += "Client: " + data + "\n";
sw.WriteLine(data);
sw.Flush();
log += "Server: " + sr.ReadLine() + "\n";

//Khai báo địa chỉ người nhận
data = "RCPT TO: <" + "phong.nd@emailserver.vn" + ">";
log += "Client: " + data + "\n";
sw.WriteLine(data);
sw.Flush();
log += "Server: " + sr.ReadLine() + "\n";

//Gửi yêu cầu báo hiệu sẽ gửi nội dung bức thư
data = "DATA";
log += "Client: " + data + "\n";
sw.WriteLine(data);
sw.Flush();
log += "Server: " + sr.ReadLine() + "\n";

//Khai báo nội dung bức thư
data = emailContent + "\r\n" + ".";
log += "Client: " + data + "\n";
sw.WriteLine(data);
sw.Flush();
log += "Server: " + sr.ReadLine() + "\n";

//Ngắt kết nối với SMTP Server hoặc Email Server
data = "QUIT";
log += "Client: " + data + "\n";
sw.WriteLine(data);
sw.Flush();
log += "Server: " + sr.ReadLine() + "\n";

sr.Close();
sw.Close();
client.Close();

    private string HMACSHA256(string message, string secret)
    {
        secret = secret ?? "";
        var encoding = new System.Text.ASCIIEncoding();
        byte[] keyByte = encoding.GetBytes(secret);
        byte[] messageBytes = encoding.GetBytes(message);
        using (var hmacsha256 = new HMACSHA256(keyByte))
        {
            byte[] hashmessage = hmacsha256.ComputeHash(messageBytes);
            string sbinary = "";
            for (int i = 0; i < hashmessage.Length; i++)
            {
                sbinary += hashmessage[i].ToString("x2"); // hex format
            }
            return sbinary;
        }
    }

string[] files = Directory.GetFiles(Environment.CurrentDirectory, "*.docx");
foreach (var file in files)
{
 System.Diagnostics.ProcessStartInfo info = new System.Diagnostics.ProcessStartInfo(file);
 info.Arguments = "\"" + printDialog1.PrinterSettings.PrinterName + "\"";
 info.CreateNoWindow = true;
 info.WindowStyle = System.Diagnostics.ProcessWindowStyle.Hidden;
 info.UseShellExecute = true;
 info.Verb = "PrintTo";
 System.Diagnostics.Process.Start(info);
}