连接代码抛出异常：无法建立连接，因为目标计算机主动拒绝它

Question

我无法连接到MySQL服务器。引发异常

  

无法建立连接，因为目标计算机主动拒绝了它mysql address ip

我不知道该怎么做，我没有自己使用的mysql服务器，我使用sql主机，所以我不能写命令。

我的C＃代码：

Database.SQLConnection sql = new Database.SQLConnection();
if(sql.IsConnect())
 {
 MySqlCommand sqlcmd = new MySqlCommand("SELECT * FROM 'users' WHERE username='" + metroTextBox1.Text + "' AND password='" + metroTextBox2.Text + "' ;", sql.GetConnection());
 MySqlDataReader dr = sqlcmd.ExecuteReader();
}

Ocph23

的数据库API

namespace Database
{
    public class SQLConnection
    {
        public SQLConnection() { }
        private string databaseName = string.Empty;
        public string DatabaseName
        {
            get { return databaseName; }
            set { databaseName = value; }
        }
        public string Password { get; set; }
        private MySqlConnection Connection = null;
        private static SQLConnection _instance = null;
        public static SQLConnection Instance()
        {
            if (_instance == null)

            _instance = new SQLConnection();
            return _instance;
        }

        public bool IsConnect()
        {
            bool result = true;
            if (Connection == null)
            {
                if (databaseName == string.Empty)
                    result = false;
                string StrCon = string.Format("Server=x; port=3306; database=x; UID=x; password=x", databaseName);
                Connection = new MySqlConnection(StrCon);
                Connection.Open();
                result = true;
            }

            return result;
        }

        public MySqlConnection GetConnection()
        {
            return Connection;
        }



        public void Close()
        {
            Connection.Close();
        }

    }
}

有什么问题？也许错误是在SQL服务器端？防火墙还是什么？