private void button1_Click(object sender, EventArgs e)
    {
        SqlConnection sqlcon = new SqlConnection(@"Data Source=(LocalDB)MSSQLLocalDB;AttachDbFilename=E:eAlati - 1366x768FastFoodDemoDBlogindb.mdf;Integrated Security=True;Connect Timeout=30");
        string query = "Select * from Table Where username = '" + txtUsername.Text.Trim() + "'and password = '" + txtPassword.Text.Trim() + "'";
        SqlDataAdapter sda = new SqlDataAdapter(query, sqlcon);
        DataTable dtbl = new DataTable();
        sda.Fill(dtbl);
        if(dtbl.Rows.Count == 1)
        {
            ucitavanje objUcitavanje = new ucitavanje();
            this.Hide();
            objUcitavanje.Show();
        }
        else
        {
            MessageBox.Show("Vaše korisničko ime ili lozinka nisu točni! Pokušajte ponovno");
        }
    }