使标签静态错误：无法通过嵌套类型“windowsForm8.Form1.DBConnect”访问外部类型“windowsForm8.Form1”的非静态成员

Question

Yo this is my first post here and i wanna know how to fix this problem in C# so im tryin to connect to database and select information from it and those information will be displayed as a label ! easy, so this is the error i get :

cannot access a non-static member of outer type 'windowsForm8.Form1' via nested Type 'windowsForm8.Form1.DBConnect'

and this is the Code :

using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using System.Windows.Forms;
using MySql.Data.MySqlClient;

namespace WindowsFormsApplication8
{
public partial class Form1 : Form
{
    public Form1()
    {
        InitializeComponent();

    }

    public class DBConnect
    {

        private MySqlConnection connection;
        private string server;
        private string database;
        private string uid;
        private string password;


        //Constructor
        public DBConnect()
        {
            Initialize();
        }

        //Initialize values
        private void Initialize()
        {
            server = "net";
            database = "rainbow";
            uid = "ok";
            password = "passwd!";
            string connectionString;
            connectionString = "SERVER=" + server + ";" + "DATABASE=" +
            database + ";" + "UID=" + uid + ";" + "PASSWORD=" + password + ";";

            connection = new MySqlConnection(connectionString);
        }

        //open connection to database
        private bool OpenConnection()
        {

            try
            {
                connection.Open();
                return true;
            }
            catch (MySqlException ex)
            {
                //When handling errors, you can your application's response based 
                //on the error number.
                //The two most common error numbers when connecting are as follows:
                //0: Cannot connect to server.
                //1045: Invalid user name and/or password.
                switch (ex.Number)
                {
                    case 0:
                        MessageBox.Show("Cannot connect to server.  Contact administrator");
                        break;

                    case 1045:
                        MessageBox.Show("Invalid username/password, please try again");
                        break;
                    default :
                        MessageBox.Show("Connected Successfuly!!");
                        break;
                }
                return false;
            }


        }

        //Close connection
        private bool CloseConnection()
        {
            try
            {
                connection.Close();
                return true;
            }
            catch (MySqlException ex)
            {
                MessageBox.Show(ex.Message);
                return false;
            }
        }

        //Insert statement
        public void Insert()
        {
            string query = "INSERT INTO mytable (username, password) VALUES('shryder', 'nopassword')";

            //open connection
            if (this.OpenConnection() == true)
            {
                //create command and assign the query and connection from the constructor
                MySqlCommand cmd = new MySqlCommand(query, connection);

                //Execute command
                cmd.ExecuteNonQuery();

                //close connection
                this.CloseConnection();
            }
        }

        //Update statement
        public void Update()
        {
        }

        //Delete statement
        public void Delete()
        {

        }

        //Select statement
        public List<string>[] Select()
        {
            string query = "SELECT * FROM mytable";

            //Create a list to store the result
            List<string>[] list = new List<string>[3];
            list[0] = new List<string>();
            list[1] = new List<string>();
            list[2] = new List<string>();

            //Open connection
            if (this.OpenConnection() == true)
            {
                //Create Command
                MySqlCommand cmd = new MySqlCommand(query, connection);
                //Create a data reader and Execute the command
                MySqlDataReader dataReader = cmd.ExecuteReader();

                //Read the data and store them in the list
                if (dataReader.Read())
                {
                    /*list[0].Add(dataReader["username"] + "");
                    list[1].Add(dataReader["password"] + "");
                    list[2].Add(dataReader["email"] + "");*/
                    newscontent.Text = dataReader["username"]; //this is the error


                }

                //close Data Reader
                dataReader.Close();

                //close Connection
                this.CloseConnection();

                //return list to be displayed
                return list;
            }
            else
            {
                return list;
            }
        }

        //Count statement


        //Backup
        public void Backup()
        {
        }

        //Restore
        public void Restore()
        {
        }
    }



}
}

please help me ,thanks :)

Answer 1

Move all your code from the class DbConnect yo your Form1 class. Then all of your methods have access to your form controls.

using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using System.Windows.Forms;
using MySql.Data.MySqlClient;

namespace WindowsFormsApplication8
{
public partial class Form1 : Form
{
    public Form1()
    {
        InitializeComponent();
    } 

        private MySqlConnection connection;
        private string server;
        private string database;
        private string uid;
        private string password;

        //Initialize values
        private void Initialize()
        {
            server = "net";
            database = "rainbow";
            uid = "ok";
            password = "passwd!";
            string connectionString;
            connectionString = "SERVER=" + server + ";" + "DATABASE=" +
            database + ";" + "UID=" + uid + ";" + "PASSWORD=" + password + ";";

            connection = new MySqlConnection(connectionString);
        }

        //open connection to database
        private bool OpenConnection()
        {

            try
            {
                connection.Open();
                return true;
            }
            catch (MySqlException ex)
            {
                //When handling errors, you can your application's response based 
                //on the error number.
                //The two most common error numbers when connecting are as follows:
                //0: Cannot connect to server.
                //1045: Invalid user name and/or password.
                switch (ex.Number)
                {
                    case 0:
                        MessageBox.Show("Cannot connect to server.  Contact administrator");
                        break;

                    case 1045:
                        MessageBox.Show("Invalid username/password, please try again");
                        break;
                    default :
                        MessageBox.Show("Connected Successfuly!!");
                        break;
                }
                return false;
            }


        }

        //Close connection
        private bool CloseConnection()
        {
            try
            {
                connection.Close();
                return true;
            }
            catch (MySqlException ex)
            {
                MessageBox.Show(ex.Message);
                return false;
            }
        }

        //Insert statement
        public void Insert()
        {
            string query = "INSERT INTO mytable (username, password) VALUES('shryder', 'nopassword')";

            //open connection
            if (this.OpenConnection() == true)
            {
                //create command and assign the query and connection from the constructor
                MySqlCommand cmd = new MySqlCommand(query, connection);

                //Execute command
                cmd.ExecuteNonQuery();

                //close connection
                this.CloseConnection();
            }
        }

        //Update statement
        public void Update()
        {
        }

        //Delete statement
        public void Delete()
        {

        }

        //Select statement
        public List<string>[] Select()
        {
            string query = "SELECT * FROM mytable";

            //Create a list to store the result
            List<string>[] list = new List<string>[3];
            list[0] = new List<string>();
            list[1] = new List<string>();
            list[2] = new List<string>();

            //Open connection
            if (this.OpenConnection() == true)
            {
                //Create Command
                MySqlCommand cmd = new MySqlCommand(query, connection);
                //Create a data reader and Execute the command
                MySqlDataReader dataReader = cmd.ExecuteReader();

                //Read the data and store them in the list
                if (dataReader.Read())
                {
                    /*list[0].Add(dataReader["username"] + "");
                    list[1].Add(dataReader["password"] + "");
                    list[2].Add(dataReader["email"] + "");*/
                    newscontent.Text = dataReader["username"]; //this is the error


                }

                //close Data Reader
                dataReader.Close();

                //close Connection
                this.CloseConnection();

                //return list to be displayed
                return list;
            }
            else
            {
                return list;
            }
        }

        //Count statement


        //Backup
        public void Backup()
        {
        }

        //Restore
        public void Restore()
        {
        }
    }



}
}

Like this your code ahould be able to access the labels, so it should compile. It still doesn't do anything since none of the methods are called.
Edited this on my phone, so couldn't test the code.