Create Login (Sign In) And Registration (Sign Up) Form In C# Windows Form With Database

private void BtnRegister_Click(object sender, EventArgs e)  
{  
    if (txtconfirmpassword.Text != string.Empty || txtpassword.Text != string.Empty || txtusername.Text != string.Empty)  
    {  
        if (txtpassword.Text == txtconfirmpassword.Text)  
        {  
            cmd = new SqlCommand("select * from LoginTable where username='" + txtusername.Text + "'", cn);  
            dr = cmd.ExecuteReader();  
            if (dr.Read())  
            {  
                dr.Close();  
                MessageBox.Show("Username Already exist please try another ", "Error", MessageBoxButtons.OK, MessageBoxIcon.Error);  
            }  
            else  
            {  
                dr.Close();  
                cmd = new SqlCommand("insert into LoginTable values(@username,@password)", cn);  
                cmd.Parameters.AddWithValue("username", txtusername.Text);  
                cmd.Parameters.AddWithValue("password", txtpassword.Text);  
                cmd.ExecuteNonQuery();  
                MessageBox.Show("Your Account is created . Please login now.", "Done", MessageBoxButtons.OK, MessageBoxIcon.Information);  
            }  
        }  
        else  
        {  
            MessageBox.Show("Please enter both password same ", "Error", MessageBoxButtons.OK, MessageBoxIcon.Error);  
        }  
    }  
    else  
    {  
        MessageBox.Show("Please enter value in all field.", "Error", MessageBoxButtons.OK, MessageBoxIcon.Error);  
    }  
}

Code Explanation

1. First of all, we check that the user entered a value in all fields. If yes, then continue, otherwise, show a message using the message box.
2. Then we check if the password and confirm password both are the same.
3. Then we check if any record/user is already registered with that username if not then continue further otherwise show an error message.
4. In last we insert data in the table using the SQLCommand object.

Step 17

Now we create a login page. Here, I added two text boxes for username and password and two buttons for a login and open registration form.

Step 18

Click on anywhere in a form which generates a Form_Load event add connection code, as shown below.

private void Login_Load(object sender, EventArgs e)  
{  
    cn = new SqlConnection(@"Data Source=(LocalDB)\MSSQLLocalDB;AttachDbFilename=H:\Website\RegistrationAndLogin\Database.mdf;Integrated Security=True");  
    cn.Open();  
}

Step 19

On a Registration button click, add the following code which opens the registration form.

private void Btnregister_Click(object sender, EventArgs e)  
{  
    this.Hide();  
    Registration registration = new Registration();  
    registration.ShowDialog();  
}

Step 20

Add the below code in the login button click for redirecting users to the home page form if the user exists.

private void BtnLogin_Click(object sender, EventArgs e)  
{  
    if (txtpassword.Text != string.Empty || txtusername.Text != string.Empty)  
    {  
  
        cmd = new SqlCommand("select * from LoginTable where username='" + txtusername.Text + "' and password='"+txtpassword.Text+"'", cn);  
        dr = cmd.ExecuteReader();  
        if (dr.Read())  
        {  
            dr.Close();  
            this.Hide();  
            Home home = new Home();  
            home.ShowDialog();  
        }  
        else  
        {  
            dr.Close();  
            MessageBox.Show("No Account avilable with this username and password ", "Error", MessageBoxButtons.OK, MessageBoxIcon.Error);  
        }  
  
    }  
    else  
    {  
        MessageBox.Show("Please enter value in all field.", "Error", MessageBoxButtons.OK, MessageBoxIcon.Error);  
    }  
}

Code Explanation

1. Here, first of all, we check if the user enters a value in both fields. If yes, then continue, otherwise, show an error message.
2. Then we check if the user exists in our database with that username and password. If the user exists, then open the home page which we generated at the start.

Step 21

Change the start page as login in Program.cs File.

static void Main()
{
    Application.EnableVisualStyles();  
    Application.SetCompatibleTextRenderingDefault(false);  
    Application.Run(new Login());  
}

Step 22

Now run your application.

Login.cs

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

namespace RegistrationAndLogin
{
    public partial class Login : Form
    {
        SqlCommand cmd;
        SqlConnection cn;
        SqlDataReader dr;

        public Login()
        {
            InitializeComponent();
        }

        private void Login_Load(object sender, EventArgs e)
        {
            cn = new SqlConnection(@"Data Source=(LocalDB)\MSSQLLocalDB;AttachDbFilename=D:\Articles\Code\RegistrationAndLogin\Database.mdf;Integrated Security=True");
            cn.Open();
        }

        private void Btnregister_Click(object sender, EventArgs e)
        {
            this.Hide();
            Registration registration = new Registration();
            registration.ShowDialog();
        }

        private void BtnLogin_Click(object sender, EventArgs e)
        {
            if (txtpassword.Text != string.Empty || txtusername.Text != string.Empty)
            {

                cmd = new SqlCommand("select * from LoginTable where username='" + txtusername.Text + "' and password='"+txtpassword.Text+"'", cn);
                dr = cmd.ExecuteReader();
                if (dr.Read())
                {
                    dr.Close();
                    this.Hide();
                    Home home = new Home();
                    home.ShowDialog();
                }
                else
                {
                    dr.Close();
                    MessageBox.Show("No Account avilable with this username and password ", "Error", MessageBoxButtons.OK, MessageBoxIcon.Error);
                }

            }
            else
            {
                MessageBox.Show("Please enter value in all field.", "Error", MessageBoxButtons.OK, MessageBoxIcon.Error);
            }
        }

    }
}

Registration.cs

using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Data.Common;
using System.Data.SqlClient;
using System.Drawing;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using System.Windows.Forms;

namespace RegistrationAndLogin
{
    public partial class Registration : Form
    {

        SqlCommand cmd;
        SqlConnection cn;
        SqlDataReader dr;

        public Registration()
        {
            InitializeComponent();
        }

        private void Registration_Load(object sender, EventArgs e)
        {
            cn = new SqlConnection(@"Data Source=(LocalDB)\MSSQLLocalDB;AttachDbFilename=D:\Articles\Code\RegistrationAndLogin\Database.mdf;Integrated Security=True");
            cn.Open();
        }

        private void BtnRegister_Click(object sender, EventArgs e)
        {
            if (txtconfirmpassword.Text != string.Empty || txtpassword.Text != string.Empty || txtusername.Text != string.Empty)
            {
                if (txtpassword.Text == txtconfirmpassword.Text)
                {
                    cmd = new SqlCommand("select * from LoginTable where username='" + txtusername.Text + "'", cn);
                    dr = cmd.ExecuteReader();
                    if (dr.Read())
                    {
                        dr.Close();
                        MessageBox.Show("Username Already exist please try another ", "Error", MessageBoxButtons.OK, MessageBoxIcon.Error);
                    }
                    else
                    {
                        dr.Close();
                        cmd = new SqlCommand("insert into LoginTable values(@username,@password)", cn);
                        cmd.Parameters.AddWithValue("username", txtusername.Text);
                        cmd.Parameters.AddWithValue("password", txtpassword.Text);
                        cmd.ExecuteNonQuery();
                        MessageBox.Show("Your Account is created . Please login now.", "Done", MessageBoxButtons.OK, MessageBoxIcon.Information);
                    }
                }
                else
                {
                    MessageBox.Show("Please enter both password same ", "Error", MessageBoxButtons.OK, MessageBoxIcon.Error);
                }
            }
            else
            {
                MessageBox.Show("Please enter value in all field.", "Error", MessageBoxButtons.OK, MessageBoxIcon.Error);
            }
        }

        private void Button1_Click(object sender, EventArgs e)
        {
            this.Hide();
            Login login = new Login();
            login.ShowDialog();
        }
    }
}

Home.cs

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;

namespace RegistrationAndLogin
{
    public partial class Home : Form
    {
        public Home()
        {
            InitializeComponent();
        }
    }
}

Program.cs

using System;
using System.Collections.Generic;
using System.Linq;
using System.Threading.Tasks;
using System.Windows.Forms;

namespace RegistrationAndLogin
{
    static class Program
    {
        /// <summary>
        /// The main entry point for the application.
        /// </summary>
        [STAThread]
        static void Main()
        {
            Application.EnableVisualStyles();
            Application.SetCompatibleTextRenderingDefault(false);
            Application.Run(new Login());
        }
    }
}

Conclusion

So here, we created a simple login and registration page in a Windows Form application. I hope you liked this article, share it with your friends.