发送电子邮件后如何更新“IsSent”列的值？

Question

我正在开发一个为用户提供简短测验的 Web 应用程序。系统将检查数据库中的 Quiz 表，该表由 QuizID 和 IsSent 列组成。

如果 IsSent 列（位数据类型）的值为 0（为 false），系统会将测验发送给所有用户。如果它有一个 1，这意味着测验已经发送。

我可以让应用程序发送电子邮件，但现在我希望系统在发送电子邮件后将 IsSent 的值更新为 1 或 true，但我不知道该怎么做。

谁能告诉我怎么做？

我的代码：

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("pssp@gmail.com", "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

首先，您当前的代码只会发送一封关于最后一次测验的电子邮件。

其次，作为一般经验法则，您应该只从数据库中检索绝对必要的数据。没有理由阅读已发送的测验，因此您可以将该查询更改为：

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

第三，您应该在发送测验的电子邮件后立即为每个测验更新 IsSent。

最后，您应该将所有收件人都作为密件抄送用户发送一封电子邮件，而不是多封电子邮件。

这是一个包含所有这些概念的重写：

    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("pssp@gmail.com", "OUR SYSTEM");

            // In case the mail system doesn't like no to recipients. This could be removed
            msg.To.Add("pssp@gmail.com");

            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();
        }
    }

Answer 2

您需要跟踪您的 QuizID，我建议使用 ArrayList，如下所示：

ArrayList quizIDs = new ArrayList();

在您的while 循环中，您遍历阅读器并将quizid 变量设置为reader["QuizID"].ToString()，添加以下行以将测验存储到列表中：

quizIDs.Add(quizid);

发送完所有电子邮件后，您需要执行查询，更新所有以前保存的 QuizID 的 IsSent 列。

这是构建更新查询的方法：

string updateQuery = "UPDATE dbo.QUIZ SET IsSent = 1 WHERE QuizID in (" + String.Join(",", quizIDs) + ")";