frmLogin

using System;
using System.Data;
using System.Windows.Forms;
using System.Data.SqlClient;
using System.Diagnostics;

namespace LoginApp
{
    public partial class frmLogin : Form
    {
        public frmLogin()
        {
            InitializeComponent();
        }

        private void btnLogin_Click(object sender, EventArgs e)
        {
            SqlConnection sqlcon = new SqlConnection(@"Data Source=(LocalDB)\MSSQLLocalDB;AttachDbFilename=C:\Users\Tom\source\repos\LoginApp\DB\LoginDB.mdf;Integrated Security=True;Connect Timeout=30");

            // Talk about issue with 'Table' being keyword for T-SQL so having to put square brackets around it
            SqlCommand command = new SqlCommand(null, sqlcon);
            command.CommandText = "SELECT * FROM [Table] WHERE username = @username AND password = @password";
            SqlParameter usernameParam = new SqlParameter("@username", SqlDbType.VarChar, 50);
            SqlParameter passwordParam = new SqlParameter("@password", SqlDbType.VarChar, 50);

            usernameParam.Value = txtUsername.Text.Trim();
            passwordParam.Value = txtPassword.Text.Trim();

            command.Parameters.Add(usernameParam);
            command.Parameters.Add(passwordParam);

            command.Prepare();
            command.ExecuteNonQuery();
            SqlDataAdapter sda = new SqlDataAdapter(command);
            DataTable dtbl = new DataTable();
            sda.Fill(dtbl);
            if(dtbl.Rows.Count ==1)
            {
                var userId = dtbl.Rows[0]["userId"];
                LoggedInUserInformation.UserID = Convert.ToInt32(userId);
                frmMain objFrmMain = new frmMain();
                this.Hide();
                objFrmMain.Show();
            }
            else
            {
                MessageBox.Show("Check your username and password");
            }
        }

        private void frmLogin_Load(object sender, EventArgs e)
        {

        }

        private void btnExit_Click(object sender, EventArgs e)
        {
            this.Close();
        }

        private void btnCreateAccount_Click(object sender, EventArgs e)
        {
            UserRegistration objUserRegistration = new UserRegistration();
            this.Hide();
            objUserRegistration.Show();
        }
    }
}