数据库中的跟踪错误

我有一个客户端-服务器程序，服务器会检查客户端是否打开了正确的应用程序。如果没有，它将显示一些警告。它应该只打开三个应用程序和正确的一个。我计划将打开的应用程序的数据和用户主机名放入数据库。将有两个表，hostnametable和processtable。示例：

主机名表

hostname_id | hostname
------------------------
      1     | Guest1
      2     | Guest2
      3     | Guest3

可处理

id | processID | processName | processExe | processPath     | hostname_id
--------------------------------------------------------------------------
1  |    4332   |  C# Basic   |  adobe.exe | C:/Users/Adm... |      2      
2  |    5400   |  PHP 101    |  ppt.exe   | C:/Users/Adm... |      2      
3  |    0943   |  Notice     |notepad.exe | C:/Users/Adm... |      1      
4  |    8932   |  Java 101   |  adobe.exe | C:/Users/Adm... |      3      
5  |    7608   |  Certific   |  word.exe  | C:/Users/Adm... |      1      
6  |    0101   |  Aliens     |  ppt.exe   | C:/Users/Adm... |      1      
7  |    8200   |  Progress   |  excel.exe | C:/Users/Adm... |      3   

一旦客户端打开一个新的应用程序，就会在服务器中发送[hostname、processID、processName、processExe、processPath]。服务器将

-通过获取主机名计数来检查主机名是否存在

-如果是，则它将选择hostname_id和

-将它与其他数据一起插入到新表中。

如果不是

-则在主机名表中插入新的主机名

-它将选择hostname_id

-并插入数据

这是一个一对多的关系，所以在后面的部分中，我需要检索它以进行输出显示和验证。我的问题是，我已经一步一步地调试了代码的数据库部分，但当我将它们作为一个整体运行时，它会在过程的最后发现一个错误。在这里它将自动进入

catch { output.Text += "'nERROR THREE'n "; }

这是我的密码。

 using (MySqlConnection conDataBase = new MySqlConnection(constring))
            {
                try
                {
                    if (exeFile == openedFile)
                    {
                        listBox1.ForeColor = System.Drawing.Color.Blue;
                        listBox1.Items.Add(machineName + " has opened the right file.");
                    }
                    else
                    {
                        string count1 = "SELECT COUNT(hostName) FROM hostnametable;";
                        string gethostname_id = "SELECT INTO chtbuster.hostnametable(hostName_id) WHERE hostName=?machineName";
                        string insert_pt = "INSERT INTO chtbuster.processtable(processID,processFileName,processName,processPath,hostName_id) VALUES (@processID, @fileName, @exeFile, @filePath, " + gethostname_id + ");";
                        string insert_ht = "INSERT INTO chtbuster.hostnametable(hostName_id) VALUES(@machineName);";
                        //query for else condition 1 is at the top
                        listBox1.ForeColor = System.Drawing.Color.Green;
                        listBox1.Items.Add(machineName + " has opened " + exeFile);
                        conDataBase.Open();
                        MySqlCommand cmd1Database = new MySqlCommand(count1, conDataBase);
                        cmd1Database.ExecuteNonQuery(); 
                        Int32 ifexist = (Int32)cmd1Database.ExecuteScalar();
                        if(ifexist>0)
                        {
                           MySqlCommand cmd2Database = new MySqlCommand(gethostname_id, conDataBase);
                            machineName = (string)cmd1Database.ExecuteScalar(); 
                            cmd2Database.Parameters.AddWithValue("?machineName", machineName);
                            MySqlCommand cmd3Database = new MySqlCommand(insert_pt, conDataBase);
                              try
                              {
                                  cmd3Database.Parameters.Clear();
                                  cmd3Database.Parameters.AddWithValue("@processID", processID);
                                  cmd3Database.Parameters.AddWithValue("@machineName", machineName);
                                  cmd3Database.Parameters.AddWithValue("@filename", fileName);
                                  cmd3Database.Parameters.AddWithValue("@exeFile", exeFile);
                                  cmd3Database.Parameters.AddWithValue("@filePath", filePath);
                                  cmd3Database.ExecuteNonQuery();
                                  cmd2Database.ExecuteReader();
                               }
                              catch (Exception ex)
                              {
                                  output.Text += "'n1" + (ex.Message);
                              } 
                        }
                        else
                        {
                           MySqlCommand cmd4Database = new MySqlCommand(Query, conDataBase);
                           MySqlCommand cmd5Database = new MySqlCommand(insert_ht, conDataBase);
                            try
                              {
                                  cmd5Database.Parameters.Clear();
                                  cmd5Database.Parameters.AddWithValue("@processID", processID);
                                  cmd5Database.Parameters.AddWithValue("@machineName", machineName);
                                  cmd5Database.Parameters.AddWithValue("@filename", fileName);
                                  cmd5Database.Parameters.AddWithValue("@exeFile", exeFile);
                                  cmd5Database.Parameters.AddWithValue("@filePath", filePath);
                                  cmd4Database.Parameters.AddWithValue("@machineName", machineName);
                                  cmd4Database.ExecuteNonQuery();
                                  cmd5Database.ExecuteNonQuery();
                                  conDataBase.Close();
                               }
                            catch (Exception ex)
                            {
                                output.Text += "'n2" + (ex.Message);
                            } 
                      }    
                    }
                }
                catch (Exception ex)
                {
                    output.Text += "'n3" + (ex.Message);
                } 
            }

 MySqlCommand cmd1Database = new MySqlCommand(count1, conDataBase);
 cmd1Database.ExecuteNonQuery(); 
 Int32 ifexist = (Int32)cmd1Database.ExecuteScalar();
 if(ifexist>0)
 {
       MySqlCommand cmd2Database = new MySqlCommand(gethostname_id, conDataBase);
       machineName = (string)cmd1Database.ExecuteScalar(); 

 int rowCount = 0;
 object result = cmd1Database.ExecuteScalar();
 if(result != null)
 {
     rowCount = (Int32) result;
 }

 object result = cmd1Database.ExecuteScalar(); 
 if(!DBNull.Value.Equals(result))
 {
      machineName = (string) result;
 }