该程序将表1中的所有记录复制到表2中，并写入文本文件。完成复制所有记录后，将删除记录，使table1为空，然后再添加新记录。我喜欢增强我的代码，例如：
提前谢谢！
//create connection
SqlConnection sqlConnection1 =
new SqlConnection("Data Source=.\SQLEXPRESS;Database=F:\Test2.mdf;Integrated Security=True;User Instance=True");
//command insert into queries
SqlCommand cmdCopy = new SqlCommand();
cmdCopy.CommandType = System.Data.CommandType.Text;
cmdCopy.CommandText = "INSERT INTO tblSend (ip, msg, date) SELECT ip, msg, date FROM tblOutbox";
cmdCopy.Connection = sqlConnection1;
//insert into text file
SqlCommand cmd = new SqlCommand();
cmd.CommandType = CommandType.Text;
cmd.CommandText = "SELECT * FROM tblOutbox";
cmd.Connection = sqlConnection1;
sqlConnection1.Open();
StreamWriter tw = File.AppendText("c:\INMS.txt");
SqlDataReader reader = cmd.ExecuteReader();
tw.WriteLine("id, ip address, message, datetime");
while (reader.Read())
{
tw.Write(reader["id"].ToString());
tw.Write(", " + reader["ip"].ToString());
tw.Write(", " + reader["msg"].ToString());
tw.WriteLine(", " + reader["date"].ToString());
}
tw.WriteLine("Report Generate at : " + DateTime.Now);
tw.WriteLine("---------------------------------");
tw.Close();
reader.Close();
//command delete
String strDel = "DELETE tblOutbox";
SqlCommand cmdDel = new SqlCommand(strDel, sqlConnection1);
//sqlConnection1.Open(); //open con
cmdCopy.ExecuteScalar();
cmd.ExecuteNonQuery(); //execute insert query
cmdDel.ExecuteScalar();//execute delete query
sqlConnection1.Close(); //close con
//*****************************************************
}
catch (System.Exception excep)
{
MessageBox.Show(excep.Message);
}
答案 0 :(得分：5)
一些建议：
无论如何，对于初学者来说。 ：）
答案 1 :(得分：4)
这肯定是一些代码，如果你愿意，我肯定可以推荐很多改进它的东西。
我要做的第一件事就是阅读IDisposable然后我会重新编写DataReader，如下所示。
using(StreamWriter tw = File.AppendText("c:\INMS.txt"))
{
using(SqlDataReader reader = cmd.ExecuteReader())
{
tw.WriteLine("id, ip_add, message, datetime");
while (reader.Read())
{
tw.Write(reader["id"].ToString());
tw.Write(", " + reader["ip_add"].ToString());
tw.Write(", " + reader["message"].ToString());
tw.WriteLine(", " + reader["datetime"].ToString());
}
tw.WriteLine(DateTime.Now);
tw.WriteLine("---------------------------------");
}
}
然后在捕获之后，将以下内容移除并关闭。
finally
{
sqlConnection1.Dispose(); //close con
}
答案 2 :(得分：2)
除了已经提供的其他一些答案之外，您可能还需要考虑使用交易来保护数据操作。
我假设您不希望以下任何操作部分完成：
cmdCopy.ExecuteScalar();
cmd.ExecuteNonQuery(); //execute insert query
cmdDel.ExecuteScalar();//execute delete query
如果您正在处理许多行，您可能希望批量更新，但这是一个完全不同的问题。
答案 3 :(得分：2)
首先感谢您努力提高自己的技能，并愿意像这样发布您的代码。我相信这是成为更好的程序员的第一步，就是拥有这种态度。
这是一个回答您的一些问题的实现。 我已经将一些旧代码提取到方法中，并将一些职责移到了自己的类中。
免责声明：
using System;
using System.Configuration;
using System.Data.SqlClient;
using System.IO;
// Program.cs
static class Program
{
[STAThread]
static void Main()
{
try
{
MailArchiver.Run();
Console.WriteLine("Application completed successfully");
}
catch (Exception ex)
{
Console.WriteLine("Unexpected error occurred:");
Console.WriteLine(ex.ToString());
}
}
}
// Reads new messages from DB, save it to a report file
// and then clears the table
public static class MailArchiver
{
public static void Run()
{
// Might be a good idea to a datetime suffix
ReportWriter.WriteFile(@"c:\INMS.txt");
CopyAndClearMessages();
}
private static void CopyAndClearMessages()
{
SqlConnection cn = DbConnectionFactory.CreateConnection();
cn.Open();
try
{
SqlTransaction tx = cn.BeginTransaction();
try
{
CopyMessages(cn, tx);
DeleteMessages(cn, tx);
tx.Commit();
}
catch
{
tx.Rollback();
throw;
}
}
finally
{
cn.Close();
}
}
private static void DeleteMessages(SqlConnection cn, SqlTransaction tx)
{
var sql = "DELETE FROM tblOutbox";
var cmd = new SqlCommand(sql, cn, tx);
cmd.CommandTimeout = 60 * 2; // timeout 2 minutes
cmd.ExecuteNonQuery();
}
private static void CopyMessages(SqlConnection cn, SqlTransaction tx)
{
var sql = "INSERT INTO tblSend (ip, msg, date) SELECT ip, msg, date FROM tblOutbox";
var cmd = new SqlCommand(sql, cn, tx);
cmd.CommandTimeout = 60 * 2; // timeout 2 minutes
cmd.ExecuteNonQuery();
}
}
// Provides database connections to the rest of the app.
public static class DbConnectionFactory
{
public static SqlConnection CreateConnection()
{
// Retrieve connection string from app.config
string connectionString = ConfigurationManager.ConnectionStrings["MailDatabase"].ConnectionString;
var cn = new SqlConnection(connectionString);
return cn;
}
}
// Writes all the data in tblOutbox to a CSV file
public static class ReportWriter
{
private static SqlDataReader GetData()
{
SqlConnection cn = DbConnectionFactory.CreateConnection();
cn.Open();
try
{
var cmd = new SqlCommand();
cmd.CommandText = "SELECT * FROM tblOutbox";
cmd.Connection = cn;
return cmd.ExecuteReader();
}
finally
{
cn.Close();
}
}
public static void WriteFile(string filename)
{
if (File.Exists(filename))
{
// This might be serious, we may overwrite data from the previous run.
// 1. You might want to throw your own custom exception here, should want to handle this
// condition higher up.
// 2. The logic added here is not the best and added for demonstration purposes only.
throw new Exception(String.Format("The file [{0}] already exists, move the file and try again"));
}
var tw = new StreamWriter(filename);
try
{
// Adds header record that describes the file contents
tw.WriteLine("id,ip address,message,datetime");
using (SqlDataReader reader = GetData())
{
while (reader.Read())
{
var id = reader["id"].ToString();
var ip = reader["ip"].ToString();
//msg might contain commas, surround value with double quotes
var msg = reader["msg"].ToString();
var date = reader["data"].ToString();
if (IfValidRecord(id, ip, msg, msg, date))
{
tw.WriteLine(string.Format("{0},{1},{2},{3}", id, ip, msg, date));
}
}
tw.WriteLine("Report generated at : " + DateTime.Now);
tw.WriteLine("--------------------------------------");
}
}
finally
{
tw.Close();
}
}
private static bool IfValidRecord(string id, string ip, string msg, string msg_4, string date)
{
// this answers your question on how to handle validation per record.
// Add required logic here
return true;
}
}
答案 4 :(得分：0)
form_load事件中，通过程序参数使表单不可见。