Setting up database in Visual Studio 2012

Question

I'm currently stuck on creating a SQL Server database in Visual Studio. I went to server explorer, created a database called UserData.mdf . Then I created a table to store usernames and passwords . I named the table LOGIN and stored a username called Faculty_ID and a password called pass123 I stored both as a Varchar(50) datatype. Everything was fine until I had to write the code for my login button.

Here's the code snippet that is giving me an error:

SqlDataAdapter("Select Count (*) From dbo.[LOGIN] where Username='" + USERNAME_txt.Text + "' and Password ='" + password_txt.Text + "'", con);

where it says:

The name Username/password does not exist in the current context

What should I rename or change?

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;
using System.Data.SqlClient;

namespace LOGINPAGE
{
    public partial class Room : Form
    {
        public Room()
        {
            InitializeComponent();
        }

        private void button2_Click(object sender, EventArgs e)
        {
            this.Close();
        }

        private void button1_Click(object sender, EventArgs e)
        {
            this.Hide();
            FloorSelection ss = new FloorSelection();
            ss.Show();
        }

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

        private void xButton1_Click(object sender, EventArgs e)
        {
            SqlConnection con = new SqlConnection(@"Data Source=(LocalDB)\v11.0;AttachDbFilename=C:\Users\Mohamed\Documents\UserData.mdf;Integrated Security=True;Connect Timeout=30");
            this.Hide();

            SqlDataAdapter sda = new SqlDataAdapter("Select Count (*) From dbo.[LOGIN] where username='" + username_txt.Text + "' and Password ='" + password_txt.Text + "'", con);

            FloorSelection ss = new FloorSelection();
            ss.Show();
        }
    }
}

Answer 1

Would recommend always put the a forms values into variable and never reading them from the form directly into a query, even for tests, otherwise you end up with a very tightly coupled test.

Have you tried this approach?

void FillLogins(string userName, string password)
    // Open connection
    using (SqlConnection c = new SqlConnection(yourConnectionString))
    {
    c.Open();
    // Create new DataAdapter / Command
    using (SqlDataAdapter a = new SqlDataAdapter(
        "Select Count (*) From dbo.[LOGIN] where Username= @userName AND Password = @password", c))
      {
        a.SelectCommand.Parameters.AddWithValue("@userName", userName);
        a.SelectCommand.Parameters.AddWithValue("@password", password);
        // Use DataAdapter to fill DataTable
        DataTable t = new DataTable();
        a.Fill(t);
      }
   }
}

Then you can call it like this (assuming you are not using databinding)

FillLogins(USERNAME_txt.Text, password_txt.Text);