我正在开发一个内联网Web应用程序，它是一个测验引擎。管理员可以通过单击指向SendingQuiz页面的链接将测验发送给数据库中的所有用户。一切运作良好，但我的问题是，即使数据库中没有测验，电子邮件也会发送给所有用户。 所以我应该如何修改此代码以避免发生此吗 的
为了您的信息，在数据库设计中，我有一个名为Quiz的表，其中包括： QuizID，标题，描述，IsSent
我现在想要的是在数据库中没有任何可用测验的情况下发送电子邮件，而不会让用户面对转储错误页面，我希望系统检查系统中是否有测验。如果没有，它不应该发送任何内容并告诉管理员数据库中没有更多的测验。 那怎么做？
我的C＃代码：
protected void SendEmail(string toAddresses, string fromAddress, string MailSubject, string MessageBody, bool isBodyHtml)
{
SmtpClient sc = new SmtpClient("Mail Server");
try
{
MailMessage msg = new MailMessage();
msg.From = new MailAddress("Test@CompanyDomain.com", "My Application");
// In case the mail system doesn't like no to recipients. This could be removed
//msg.To.Add("Test@CompanyDomain.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=Test;Integrated Security=True";
using (SqlConnection conn = new SqlConnection(connString))
{
var sbEmailAddresses = new System.Text.StringBuilder(2000);
string quizid = "";
// Open DB connection.
conn.Open();
string cmdText = "SELECT MIN (QuizID) As mQuizID 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
quizid = reader["mQuizID"].ToString();
}
}
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("@CompanyDomain.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);
var sEMailAddresses = sbEmailAddresses.ToString();
string link = "<a href='http://Test/StartQuiz.aspx?testid=" + quizid + "'> Click here to participate </a>";
string body = @"Good day, <br /><br />
<b> Please participate in the new short safety quiz </b>"
+ link +
@"<br /><br />
";
int sendCount = 0;
List<string> addressList = new List<string>(sEMailAddresses.Split(','));
StringBuilder addressesToSend = new StringBuilder();
for (int userIndex = 0; userIndex < addressList.Count; userIndex++)
{
sendCount++;
if (addressesToSend.Length > 0)
addressesToSend.Append(",");
addressesToSend.Append(addressList[userIndex]);
if (sendCount == 10 || userIndex == addressList.Count - 1)
{
SendEmail(addressesToSend.ToString(), "", "Notification of New Weekly Safety Quiz", body, true);
addressesToSend.Clear();
sendCount = 0;
}
}
// Update the parameter for the current quiz
oParameter.Value = quizid;
// And execute the command
cmd.ExecuteNonQuery();
}
conn.Close();
}
}
答案 0 :(得分：0)
最简单的解决方案是执行标量查询以确定行数：
SELECT COUNT(*) FROM Quiz
如果大于零，表格中会有测验！
答案 1 :(得分：0)
你已经得到了quizid。如果它为null，则向管理员发送电子邮件并返回，否则先于...？
答案 2 :(得分：0)
你不需要为读者使用While，因为你只期望一个quizid，你可以使用if子句在发送邮件之前检查是否有quizid
protected void SendEmail(string toAddresses, string fromAddress, string MailSubject, string MessageBody, bool isBodyHtml)
{
SmtpClient sc = new SmtpClient("MAIL.Aramco.com");
try
{
MailMessage msg = new MailMessage();
msg.From = new MailAddress("pssp@aramco.com", "PMOD Safety Services Portal (PSSP)");
// In case the mail system doesn't like no to recipients. This could be removed
//msg.To.Add("pssp@aramco.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=psspdbTest;Integrated Security=True";
using (SqlConnection conn = new SqlConnection(connString))
{
var sbEmailAddresses = new System.Text.StringBuilder(2000);
string quizid = "";
// Open DB connection.
conn.Open();
string cmdText = "SELECT MIN (QuizID) As mQuizID FROM dbo.QUIZ WHERE IsSent <> 1";
using (SqlCommand cmd = new SqlCommand(cmdText, conn))
{
SqlDataReader reader = cmd.ExecuteReader();
if (reader != null)
{
if(reader.Read())
{
// There is only 1 column, so just retrieve it using the ordinal position
quizid = reader["mQuizID"].ToString();
}
}
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("@aramco.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);
var sEMailAddresses = sbEmailAddresses.ToString();
string link = "<a href='http://pmv/pssp/StartQuiz.aspx?testid=" + quizid + "'> Click here to participate </a>";
string body = @"Good day, <br /><br />
<b> Please participate in the new short safety quiz </b>"
+ link +
@"<br /><br />
Also, give yourself a chance to gain more safety culture by reading the PMOD Newsletter.
<br /> <br /><br /> <br />
This email was generated using the <a href='http://pmv/pssp/Default.aspx'>PMOD Safety Services Portal (PSSP) </a>.
Please do not reply to this email.
";
int sendCount = 0;
List<string> addressList = new List<string>(sEMailAddresses.Split(','));
StringBuilder addressesToSend = new StringBuilder();
if(!string.IsNullOrEmpty(quizid )){
for (int userIndex = 0; userIndex < addressList.Count; userIndex++)
{
sendCount++;
if (addressesToSend.Length > 0)
addressesToSend.Append(",");
addressesToSend.Append(addressList[userIndex]);
if (sendCount == 10 || userIndex == addressList.Count - 1)
{
SendEmail(addressesToSend.ToString(), "", "Notification of New Weekly Safety Quiz", body, true);
addressesToSend.Clear();
sendCount = 0;
}
}
}
// Update the parameter for the current quiz
oParameter.Value = quizid;
// And execute the command
cmd.ExecuteNonQuery();
}
conn.Close();
}
}
答案 3 :(得分：0)
在SendEmailTOAllUser中使用块选择最小的quizid之后，你应该检查quizid是否为null并将代码嵌入到conn.Close（）中。