Question

I am developing a web application that provides the users with short quizzes. The system will check the Quiz table in the database which consists of a QuizID and IsSent column.

If the IsSent column (which is a bit data type) has a value of 0 (which is false), the system will send the quiz to all users. If it has a 1, this means the quiz has already been sent.

I am able to let the application sends emails, but now I want the system to update the value of IsSent to 1 or true after sending the email but I don’t know how to do it.

Can anyone tell me how to do it?

My Code:

protected void Page_Load(object sender, EventArgs e)
{
    SendEmailTOAllUser();
}


protected void SendEmail(string toAddress, string fromAddress, string MailSubject, string MessageBody, bool isBodyHtml) 
{
    SmtpClient sc = new SmtpClient("SMTP (MAIL) ADDRESS");
    try
    {
        MailMessage msg = new MailMessage();
        msg.From = new MailAddress("[e-mail]", "OUR SYSTEM");
        msg.To.Add(toAddress);
        msg.Subject = MailSubject;
        msg.Body = MessageBody;
        msg.IsBodyHtml = isBodyHtml;
        //Response.Write(msg);
        sc.Send(msg);
    }
    catch (Exception ex)
    {
        throw ex;
    }

}

protected void SendEmailTOAllUser()
{
    string connString = "Data Source=localhost\\sqlexpress;Initial Catalog=psspTest;Integrated Security=True";
    string cmdText = "SELECT QuizID, IsSent FROM dbo.QUIZ";
    string cmdText2 = "SELECT Username FROM dbo.employee";

    Collection<string> emailAddresses = new Collection<string>();
    string link = "";
    string body = "";

    using (SqlConnection conn = new SqlConnection(connString))
    {
        conn.Open();
        // Open DB connection.
        using (SqlCommand cmd = new SqlCommand(cmdText, conn))
        {
            SqlDataReader reader = cmd.ExecuteReader();
            if (reader != null)
            {
                while (reader.Read())
                {
                    if (!(bool)reader["IsSent"])
                    {
                        string quizid = reader["QuizID"].ToString();
                        link = "<a href='http://pmv/pssp/StartQuiz.aspx?testid=" + quizid + "'> Click here to participate </a>";
                        body = @"<b> Please try to participate in the new short safety quiz </b>"
                                            + link +
                                            @"<br /> <br />
                        This email was generated using the <a href='http://pmv/pssp/Default.aspx'>PMOD Safety Services Portal </a>. 
                        Please do not reply to this email.
                        ";    
                    }
                }
            }
            reader.Close();
        }

        using (SqlCommand cmd = new SqlCommand(cmdText2, conn))
        {
            SqlDataReader reader = cmd.ExecuteReader();
            if (reader != null)
            {
                while (reader.Read())
                {
                    string emailTo = reader["Username"].ToString();
                    string receiverEmail = emailTo + "@gmail.com";
                    emailAddresses.Add(receiverEmail);
                }
            }
            reader.Close();
        }
        conn.Close();
    }

    foreach (string email in emailAddresses)
    {
        SendEmail(email, "", "Notification Email Subject", body, true);
    }
}

Answer 1

First, your code as it currently stands, will only send an email about the last quiz.

Second, as a general rule of thumb, you should only retrieve the data that is absolutely necessary from the database. There is no reason to read in quizzes that have already been sent, so you can change that query to:

string cmdText = "SELECT QuizID FROM dbo.QUIZ WHERE IsSent <> 1";

Third, you should update IsSent for each quiz immediately after the emails for the quiz have been sent.

Finally, you should send a single email with all recipients as BCC users rather than multiple emails.

Here is a rewrite containing all of these concepts:

    protected void SendEmail(string toAddresses, string fromAddress, string MailSubject, string MessageBody, bool isBodyHtml)
    {
        SmtpClient sc = new SmtpClient("SMTP (MAIL) ADDRESS");
        try
        {
            MailMessage msg = new MailMessage();
            msg.From = new MailAddress("[e-mail]", "OUR SYSTEM");

            // In case the mail system doesn't like no to recipients. This could be removed
            msg.To.Add("[e-mail]");

            msg.Bcc.Add(toAddresses);
            msg.Subject = MailSubject;
            msg.Body = MessageBody;
            msg.IsBodyHtml = isBodyHtml;
            //Response.Write(msg);
            sc.Send(msg);
        }
        catch (Exception ex)
        {
            throw ex;
        }

    }

    protected void SendEmailTOAllUser()
    {
        string connString = "Data Source=localhost\\sqlexpress;Initial Catalog=psspTest;Integrated Security=True";

        using (SqlConnection conn = new SqlConnection(connString))
        {
            var sbEmailAddresses = new System.Text.StringBuilder(1000);
            var quizIds = new List<int>();

            // Open DB connection.
            conn.Open();

            string cmdText = "SELECT QuizID FROM dbo.QUIZ WHERE IsSent <> 1";
            using (SqlCommand cmd = new SqlCommand(cmdText, conn))
            {
                SqlDataReader reader = cmd.ExecuteReader();
                if (reader != null)
                {
                    while (reader.Read())
                    {
                        // There is only 1 column, so just retrieve it using the ordinal position
                        quizIds.Add(reader.GetInt32(0));
                    }
                }
                reader.Close();
            }

            string cmdText2 = "SELECT Username FROM dbo.employee";
            using (SqlCommand cmd = new SqlCommand(cmdText2, conn))
            {
                SqlDataReader reader = cmd.ExecuteReader();
                if (reader != null)
                {
                    while (reader.Read())
                    {
                        var sName = reader.GetString(0);
                        if (!string.IsNullOrEmpty(sName)
                        {
                            if (sbEmailAddresses.Length != 0)
                            {
                                sbEmailAddresses.Append(",");
                            }
                            // Just use the ordinal position for the user name since there is only 1 column
                            sbEmailAddresses.Append(sName).Append("@gmail.com");
                        }
                    }
                }
                reader.Close();
            }

            string cmdText3 = "UPDATE dbo.Quiz SET IsSent = 1 WHERE QuizId = @QuizID";
            using (SqlCommand cmd = new SqlCommand(cmdText3, conn))
            {
                // Add the parameter to the command
                var oParameter = cmd.Parameters.Add("@QuizID", SqlDbType.Int);
                // Get a local copy of the email addresses
                var sEMailAddresses = sbEmailAddresses.ToString();

                foreach (int quizid in quizIds)
                {
                    string link = "<a href='http://pmv/pssp/StartQuiz.aspx?testid=" + quizid + "'> Click here to participate </a>";
                    string body = @"<b> Please try to participate in the new short safety quiz </b>"
                                        + link +
                                        @"<br /> <br />
                    This email was generated using the <a href='http://pmv/pssp/Default.aspx'>PMOD Safety Services Portal </a>. 
                    Please do not reply to this email.
                    ";

                    SendEmail(sEMailAddresses, "", "Notification Email Subject", body, true);

                    // Update the parameter for the current quiz
                    oParameter.Value = quizid;
                    // And execute the command
                    cmd.ExecuteNonQuery();
                }
            }
            conn.Close();
        }
    }