Question

我有一个Windows窗体程序，用于管理业务。我将所有客户详细信息保留在链接的数据库中。电子邮件地址。我有一个按钮，可让我向邮件列表中的所有人发送电子邮件（以下代码）。但是在发送了一些带有未指定错误的电子邮件后，它崩溃了。我不知道为什么？我需要它立即从CustomerID40-CustomerID1425向所有客户发送相同的电子邮件，我们将不胜感激。对不起，如果代码混乱。谢谢。错误：

System.Data.OleDb.OleDbException

HResult = 0x80004005

Message =未指定错误

Source = System.Data

StackTrace：
     在
  System.Data.OleDb.OleDbConnectionInternal..ctor（OleDbConnectionString   constr，OleDbConnection连接）
     在
  System.Data.OleDb.OleDbConnectionFactory.CreateConnection（DbConnectionOptions   选项，DbConnectionPoolKey poolKey，对象poolGroupProviderInfo，   DbConnectionPool池，DbConnection owneringObject）
     在
  System.Data.ProviderBase.DbConnectionFactory.CreateConnection（DbConnectionOptions   选项，DbConnectionPoolKey poolKey，对象poolGroupProviderInfo，   DbConnectionPool池，DbConnection owningConnection，   DbConnectionOptions userOptions）
     在
  System.Data.ProviderBase.DbConnectionFactory.CreateNonPooledConnection（DbConnection   owningConnection，DbConnectionPoolGroup，poolGroup，DbConnectionOptions   userOptions）
     在
  System.Data.ProviderBase.DbConnectionFactory.TryGetConnection（DbConnection   owningConnection，TaskCompletionSource`1重试，DbConnectionOptions   userOptions，DbConnectionInternal oldConnection，DbConnectionInternal＆   连接）
     在
  System.Data.ProviderBase.DbConnectionInternal.TryOpenConnectionInternal（DbConnection   externalConnection，DbConnectionFactory connectionFactory，   TaskCompletionSource`1重试，DbConnectionOptions userOptions）
     在
  System.Data.ProviderBase.DbConnectionClosed.TryOpenConnection（DbConnection   externalConnection，DbConnectionFactory connectionFactory，   TaskCompletionSource`1重试，DbConnectionOptions userOptions）
     在
  System.Data.ProviderBase.DbConnectionInternal.OpenConnection（DbConnection   externalConnection，DbConnectionFactory connectionFactory）

在System.Data.OleDb.OleDbConnection.Open（）

位于CourseworkDatabase.clsDBConnector.Connect（）中   C：\ Users \ rep \ OneDrive \ Desktop \ Repairs \ Repairs_Database \ CourseworkDatabase \ CourseworkDatabase \ clsDBConnector.cs：第18行

代码：

private void button6_Click_1(object sender, EventArgs e)
{
    DialogResult dialogResult = MessageBox.Show("Are you sure to send email to all customers?(check code)", "Warning", MessageBoxButtons.YesNo);
    if (dialogResult == DialogResult.Yes)
    {
        DoButtonTask();
    }
}
private void DoButtonTask()
{
    for (int i = 40; i < 1425; i++) //40-1425 is customerID's
    {
        clsDBConnector dbConnector1 = new clsDBConnector();
        OleDbDataReader dr1;
        string sqlStr1;
        dbConnector1.Connect();
        sqlStr1 = " SELECT CustomerID, DateAdded, FullName, PhoneNumber, EmailAddress, SendOffersByEmail" +
            " FROM Customer" + 
            " WHERE (CustomerID = " + i + ")";
        dr1 = dbConnector1.DoSQL(sqlStr1);
        string name = "";
        string CustomerID = "";
        string email = "";
        string SendOffersBy_Email = "";
        DateTime date = DateTime.Now;
        while (dr1.Read())
        {    
            CustomerID = CustomerID + Convert.ToString(dr1[0]);
            name = name + dr1[2];
            email = email + Convert.ToString(dr1[4]);
            SendOffersBy_Email = SendOffersBy_Email + Convert.ToString(dr1[5]);
        }
        if (email == "na" || email == "na@na.co.uk" || email == "na@na.com" || email == "")
        {
            //MessageBox.Show("Customer " + CustomerID + " does not have an email linked.");
        }
        else
        {
            if (SendOffersBy_Email == "yes" || SendOffersBy_Email == "Yes")
            {    
                try
                {    
                    SendEmail(i, email, name);
                }
                catch (Exception ex)
                {    
                    MessageBox.Show(ex.ToString());
                }
            }
            else
            {   
                //MessageBox.Show("Customer " + CustomerID + " does not accept emails.");
            }
        }
    }
    MessageBox.Show("Emails sent.");
}

private void SendEmail(int i, string email, string name)
{    
    try
    {    
        MailMessage mail = new MailMessage();
        SmtpClient SmtpServer = new SmtpClient("smtp.live.com");
        mail.From = new MailAddress("myemail");
        mail.To.Add(email);
        mail.Subject = "PRICE DROP!! Have your iPhone repaired today.";
        mail.Body = "Hi " + name + ",\n" + 
            "Our iPhone 7 and iPhone 8 series screen prices have now dropped in price!" + 
            " Reply to this email to have your iPhone booked in for repair today - the prices may go back up! " + 
            " All of our repairs come with our 6 months warranty and we can come to you." + 
            "\n\nKind regards,\n Your Mobile Phone & Tablet Repair Specialist." + 
            "\n\nTel: \nWebsite: \nEmail: " + 
            "\nFacebook: " + 
            "\n\n\n Don't want to recieve offers anymore? Just reply to this email to let us know and we will take you off our mailing system.";

        SmtpServer.Port = 587;
        SmtpServer.Credentials = new System.Net.NetworkCredential("myemail", "mypassword");
        SmtpServer.EnableSsl = true;
        SmtpServer.Send(mail);
        mail.Dispose();
    }
    catch (Exception ex)
    {    
        MessageBox.Show(ex.ToString());
    }
}

Answer 1

代码有明显的改进：

    for (int i = 40; i < 1425; i++) //40-1425 is customerID's
    {
        clsDBConnector dbConnector1 = new clsDBConnector();
        OleDbDataReader dr1;
        string sqlStr1;
        dbConnector1.Connect(); 
        ...
   }

此代码会在每次遇到问题时打开数据库，这会增加开销，并且您的防病毒软件可能每次都在检查文件。

我建议将连接移到循环之外（并关闭），这样它就会变成

clsDBConnector dbConnector1 = new clsDBConnector();
OleDbDataReader dr1;
string sqlStr1;
dbConnector1.Connect();
for (int i = 40; i < 1425; i++) //40-1425 is customerID's
{
   // process data
}
dbConnector1.Close();

Answer 2

尝试一下：

将数据库检索移动到单独的功能中。

仅执行一个查询即可获取所有数据并放入一个结构中。

private void button6_Click_1(object sender, EventArgs e)
{
    DialogResult dialogResult = MessageBox.Show("Are you sure to send email to all customers?(check code)", "Warning", MessageBoxButtons.YesNo);
    if (dialogResult == DialogResult.Yes)
    {
        DoButtonTask();
    }
}
private class Customer
{
    public string CustomerID {get; set;}
    public string Name {get; set;}
    public string Email {get; set;}
    public string SendOffersBy_Email {get; set;}     
}
private List<Customer> getCustomers(string query)
{
    List<Customer> output = new List<Customer>();
    try
    {        
        clsDBConnector dbConnector1 = new clsDBConnector();
        OleDbDataReader dr1;
        dbConnector1.Connect();

        dr1 = dbConnector1.DoSQL(query);

        while (dr1.Read())
        {   
            Customer c = new Customer();
            c.CustomerID = Convert.ToString(dr1[0]);
            c.Name = dr1[2];
            c.Email = Convert.ToString(dr1[4]);
            c.SendOffersBy_Email = Convert.ToString(dr1[5]);
            output.Add(c);
        }
    }
    catch (Exception ex)
    {    
        MessageBox.Show(ex.ToString());
    }
    finally
    {
        return output;
    }

}
private void DoButtonTask()
{
    int minCustomerID = 40;
    int maxCustomerID = 1425;
    string  sqlStr1 = "SELECT CustomerID, DateAdded, FullName, PhoneNumber, EmailAddress, SendOffersByEmail" +
        " FROM Customer WHERE CustomerID >= " + minCustomerID + " and CustomerID < " + maxCustomerID + ";" ;

    List<Customer> aCustomers = getCustomers(sqlStr1);

    foreach (customer in aCustomers)
    {
        string email = customer.Email;
        if (email == "na" || email == "na@na.co.uk" || email == "na@na.com" || email == "")
        {
            //MessageBox.Show("Customer " + customer.CustomerID + " does not have an email linked.");
        }
        else
        {
            if (customer.SendOffersBy_Email == "yes" || customer.SendOffersBy_Email == "Yes")
            {    
               SendEmail(i, email, customer.Name);
            }
            else
            {   
                //MessageBox.Show("Customer " + CustomerID + " does not accept emails.");
            }
        }
    }

    MessageBox.Show("Emails sent.");
}

private void SendEmail(int i, string email, string name)
{    
    try
    {    
        MailMessage mail = new MailMessage();
        SmtpClient SmtpServer = new SmtpClient("smtp.live.com");
        mail.From = new MailAddress("myemail");
        mail.To.Add(email);
        mail.Subject = "PRICE DROP!! Have your iPhone repaired today.";
        mail.Body = "Hi " + name + ",\n" + 
            "Our iPhone 7 and iPhone 8 series screen prices have now dropped in price!" + 
            " Reply to this email to have your iPhone booked in for repair today - the prices may go back up! " + 
            " All of our repairs come with our 6 months warranty and we can come to you." + 
            "\n\nKind regards,\n Your Mobile Phone & Tablet Repair Specialist." + 
            "\n\nTel: \nWebsite: \nEmail: " + 
            "\nFacebook: " + 
            "\n\n\n Don't want to recieve offers anymore? Just reply to this email to let us know and we will take you off our mailing system.";

        SmtpServer.Port = 587;
        SmtpServer.Credentials = new System.Net.NetworkCredential("myemail", "mypassword");
        SmtpServer.EnableSsl = true;
        SmtpServer.Send(mail);
        mail.Dispose();
    }
    catch (Exception ex)
    {    
        MessageBox.Show(ex.ToString());
    }
}

使用循环c＃

代码：

2 个答案: