Windows Forms: Create Login Form with SQL Server in C#

Step 1: Click New Project, then select Visual C# on the left, then Windows and then select Windows Forms Application. Name your project "LoginForm" and then click OK

Step 2: Design your login form as below

Step 3: Create a user table, then add the user table to Entity Framework Model First as below

Step 4: Add a click event handler to the button

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

        private void txtUsername_KeyPress(object sender, KeyPressEventArgs e)
        {
            if (e.KeyChar == (char)13)//Enter key
                txtPassword.Focus();
        }

        private void txtPassword_KeyPress(object sender, KeyPressEventArgs e)
        {
            if (e.KeyChar == (char)13)
                btnLogin.PerformClick();
        }

        private void btnLogin_Click(object sender, EventArgs e)
        {
            if (string.IsNullOrEmpty(txtUsername.Text))
            {
                MessageBox.Show("Please enter your username.", "Message", MessageBoxButtons.OK, MessageBoxIcon.Warning);
                txtUsername.Focus();
                return;
            }
            try
            {
                using (TestEntities test = new TestEntities())
                {
                    //using linq to query data
                    var query = from o in test.Users
                                where o.Username == txtUsername.Text && o.Password == txtPassword.Text
                                select o;
                    //check if user exists
                    if (query.SingleOrDefault() != null)
                    {
                        MessageBox.Show("You have been successfully logged in.", "Message", MessageBoxButtons.OK, MessageBoxIcon.Information);
                        //Add your code process login here
                    }
                    else
                    {
                        MessageBox.Show("Your username or password is incorrect.", "Message", MessageBoxButtons.OK, MessageBoxIcon.Information);
                    }
                }
            }
            catch (Exception ex)
            {
                MessageBox.Show(ex.Message, "Message", MessageBoxButtons.OK, MessageBoxIcon.Error);
            }
        }
    }
}

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