我自己也遇到过这个问题，这是我的 sqlclass：
namespace Chat
{
internal class DBConnect
{
private MySqlConnection _connection = new MySqlConnection();
private MySqlConnection _register = new MySqlConnection();
private MySqlConnection _userdata = new MySqlConnection();
private string _server;
private string _database;
private string _uid;
private string _password;
public String MessageRecieved;
//private string _table = "testconnectie";
private string _port;
//private bool succes = false;
//Constructor
public DBConnect()
{
InitializeChat();
InitializeRegister();
}
//Initialize values
public void InitializeChat()
{
_server = "localhost";
_port = "3307";
_database = "test";
_uid = "root";
_password = "usbw";
string connectionString = "Server=" + _server + ";" + "Port=" + _port +";" + "Database=" +
_database + ";" + "Uid=" + _uid + ";" + "Pwd=" + _password + ";";
_connection = new MySqlConnection(connectionString);
}
public void InitializeUserData()
{
_server = "localhost";
_port = "3307";
_uid = "root";
_password = "usbw";
string connectionString = "Server=" + _server + ";" + "Port=" + _port + ";" + "Database=" +
_database + ";" + "Uid=" + _uid + ";" + "Pwd=" + _password + ";";
_connection = new MySqlConnection(connectionString);
}
public void InitializeRegister()
{
_server = "localhost";
_port = "3307";
_database = "testlogin";
_uid = "root";
_password = "usbw";
string registerString = "Server=" + _server + ";" + "Port=" + _port + ";" + "Database=" +
_database + ";" + "Uid=" + _uid + ";" + "Pwd=" + _password + ";";
_register = new MySqlConnection(registerString);
}
public bool OpenConnection()
{
try
{
_register.Open();
return true;
}
catch (MySqlException ex)
{
switch (ex.Number)
{
case 0:
MessageBox.Show("Cannot connect to server");
break;
case 1042:
MessageBox.Show("Unable to connect to any of the specified MySQL hosts");
break;
case 1045:
MessageBox.Show("Invalid username/password");
break;
}
return false;
}
}
public void Select()
{
string selectquery = "SELECT * FROM testconnectie";
MySqlCommand cmd = new MySqlCommand(selectquery, _connection);
MySqlDataReader dataReader = cmd.ExecuteReader();
_messagelist.Clear();
while (dataReader.Read())
{
_messagelist.Add(dataReader["time"] + " ");
_messagelist.Add(dataReader["text"] + "\r\n");
}
dataReader.Close();
MessageRecieved = _messagelist.ToString();
}
public void Insert(string textvalue)
{
//DateTime dt = DateTime.Parse("6/22/2009 07:00:00 AM");
//dt.ToString("H:mm"); // 7:00 // 24 hour clock
//var now = DateTime.Now;
//var minutes = now.Minute;
//var hour = now.Hour;
//var time = now;
string time = DateTime.Now.ToString("HH:mm:ss");
string insertquery = "INSERT INTO testconnectie(time, text) VALUES ('"+time+"','"+textvalue+"')";
try
{
MySqlCommand cmd = new MySqlCommand(insertquery, _connection);
cmd.ExecuteNonQuery();
}
catch (Exception ex)
{
MessageBox.Show("Error(1)" + ex);
}
}
private void Update()
{
string updatequery = "UPDATE tabelnaam SET waarde='', waarde'' WHERE waarde=''";
MySqlCommand cmd = new MySqlCommand();
cmd.CommandText = updatequery;
cmd.Connection = _connection;
cmd.ExecuteNonQuery();
}
private void Delete()
{
string deletequery = "DELETE FROM tabelnaam WHERE waarde=''";
MySqlCommand cmd = new MySqlCommand(deletequery, _connection);
cmd.ExecuteNonQuery();
}
public bool CloseConnection()
{
try
{
_connection.Close();
return true;
}
catch (MySqlException ex)
{
MessageBox.Show(ex.Message);
return false;
}
}
public void Backup()
{
try
{
DateTime Time = DateTime.Now;
int year = Time.Year;
int month = Time.Month;
int day = Time.Day;
int hour = Time.Hour;
int minute = Time.Minute;
int second = Time.Second;
int millisecond = Time.Millisecond;
//Save file to C:\ with the current date as a filename
string path;
path = "C:\\ChatBackup" + year + "-" + month + "-" + day +
"-" + hour + "-" + minute + "-" + second + "-" + millisecond + ".sql";
StreamWriter file = new StreamWriter(path);
ProcessStartInfo psi = new ProcessStartInfo();
psi.FileName = "Database Backup";
psi.RedirectStandardInput = false;
psi.RedirectStandardOutput = true;
psi.Arguments = string.Format(@"-u{0} -p{1} -h{2} {3}",
_uid, _password, _server, _database);
psi.UseShellExecute = false;
Process process = Process.Start(psi);
string output;
output = process.StandardOutput.ReadToEnd();
file.WriteLine(output);
process.WaitForExit();
file.Close();
process.Close();
}
catch (IOException ex)
{
MessageBox.Show("Error , unable to backup! " + ex);
}
}
}
}
希望这有助于它可能有点大，但只需使用您需要的功能
你可以做的是使用项目属性中的设置来存储你所有的连接数据。
所以你可以把 serverIp、Port、Database、Uid 和密码放在 de setting 选项卡中。
你可以这样称呼他们：Properties.Settings.Default.serverIp
它更容易，所以最后你可以这样做：
string serverIp = Properties.Setting.Default.serverIp;
string port = Properties.Setting.Default.port;
string username = Properties.Setting.Default.Uid;
等等。
也可以尝试更改连接字符串中的UID Uid
您也捕获了异常但您不使用它，在这种情况下，默认值应显示为异常，以便您理解它。你可以这样做：
label1.Text = "Error: " + ex.Message;