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I am new in Programming line please give me the code to connect Mysql Database with C# in windows Form.
I made a program of login and i create a Mysql databse but when i goes to connect the form with database& written whole code i encounter a problem That "error with database connection" and it show exception in code line

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

namespace Login
{
    public partial class Form1 : Form
    {
        private MySqlConnection connection;
        private string server;
        private string database;
        private string uid;
        private string password;

        public Form1()
        {
            InitializeComponent();
        }
        private void Initialize()
        {
            server = "localhost";
            database = "diary";
            uid = "root";
            password = "12345";
            string connectionString;
            connectionString = "SERVER=" + server + ";" + "DATABASE=" +
            database + ";" + "UID=" + uid + ";" + "PASSWORD=" + password + ";";

            connection = new MySqlConnection(connectionString);
        }


        private void button1_Click(object sender, EventArgs e)
        {
           try
            {
                connection.Open();
                string qry1 = "Select * from login where Password=@Password and Username=@Username";
                MySqlCommand com = new MySqlCommand(qry1, connection);
                com.Parameters.AddWithValue("@Username", this.textBox1.Text);
                com.Parameters.AddWithValue("@Password", this.textBox2.Text);
                MySqlDataReader dr = com.ExecuteReader();// this line show the exception....

                while (dr.Read())
                {
                    if (dr.HasRows == true)
                    {
                        MessageBox.Show("Login Successfull", "Login Information");
                        this.Hide();
                        home h = new home();
                        h.Show();
                    }
                }
                if (dr.HasRows == false)
                {
                    MessageBox.Show("Access Denied", "Login Information");
                    this.Close();

                }
                connection.Close();
            }
            catch (Exception)
            {
                MessageBox.Show("Error with the database connection");
            }


        }    

      private void label3_Click(object sender, EventArgs e)
        {

        }

        private void Form1_Load(object sender, EventArgs e)
        {

        } 

    }
}
7
Contributors
8
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4 Years
Discussion Span
Last Post by JOSheaIV
0

NullReferenceException was unhandled, Object Reference not set to an instance of an object

0

Check you database connection state i.e connection is open or not...
or you can code this way if connection is closed then open it.best practices in c#

if(connection.state==connection.closed)
{
    connection.Open();
}
0

I believe it's your Connection String. I did a quick search for the format of a MySQL connection string

Server=myServerAddress;Database=myDataBase;Uid=myUsername;Pwd=myPassword;

Look at your password part. You did "PASSWORD=", when it should be "Pwd="

That would explain the error you are getting to (it never even makes a connection)

0

I doubt the OP is even watching this thread considering he hasn't posted for a couple of years :)

This topic has been dead for over six months. Start a new discussion instead.
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