Problem Using SQL database C#

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C#

I am learning how to use database in c# for that i have created an application that checks or adds user
Problem is that
1.when ever solution is running the values are added to database and are shown but as soon as i recompile the solution then all the previous data is gone
2.what ever data i store in database it gets stored with spaces at its end for eg user name entered in text box is Afnan it gets stored and displayed with spaces as Afnan........ where . represent space.
I added MDF file and created table in that.

using System;<br />
using System.Collections.Generic;<br />
using System.ComponentModel;<br />
using System.Data;<br />
using System.Drawing;<br />
using System.Linq;<br />
using System.Text;<br />
using System.Windows.Forms;<br />
using System.Data.SqlClient;<br />
using System.Data.Sql;<br />
namespace Neo_Soft_Project_Manegment<br />
{<br />
    public partial class Form1 : Form<br />
    {<br />
        public Form1()<br />
        {<br />
            InitializeComponent();<br />
        }<br />
<br />
     <br />
        private void Form1_Load(object sender, EventArgs e)<br />
        {<br />
<br />
           // MessageBox.Show(usersTableAdapter1.);<br />
<br />
        }<br />
<br />
        private void button_login_Click(object sender, EventArgs e)<br />
        {<br />
     <br />
            string connectionString = @"Data Source=.\SQLEXPRESS;AttachDbFilename=|DataDirectory|\Database1.mdf;Integrated Security=True;User Instance=True";<br />
            SqlConnection cn = new SqlConnection(connectionString);<br />
            try<br />
            {<br />
                cn.Open();<br />
              <br />
            }<br />
            catch<br />
            {<br />
                MessageBox.Show("Unable to connect");<br />
            }<br />
<br />
            string Uname = text_user.Text;<br />
            string Pass = text_pass.Text;<br />
            string sqlquery = ("SELECT*FROM Users WHERE user_name = '" + text_user.Text + "'");<br />
            sqlquery = " INSERT INTO [Users](user_name,user_pass) VALUES ('"+text_user.Text+"','"+text_pass.Text+"')";<br />
            SqlCommand command = new SqlCommand(sqlquery, cn);<br />
            command.ExecuteNonQuery();<br />
            <br />
            if (command != null)<br />
                command.Dispose();<br />
            if (cn != null)<br />
                cn.Close();            <br />
        }<br />
<br />
        private void button1_Click(object sender, EventArgs e)<br />
        {<br />
            string connectionString = @"Data Source=.\SQLEXPRESS;AttachDbFilename=|DataDirectory|\Database1.mdf;Integrated Security=True;User Instance=True";<br />
            SqlConnection cn = new SqlConnection(connectionString);<br />
            try<br />
            {<br />
                cn.Open();<br />
            }<br />
            catch<br />
            {<br />
                MessageBox.Show("Unable to connect");<br />
            }<br />
            SqlCommand cmd = new SqlCommand("SELECT * FROM Users", cn);<br />
            cmd.Connection = cn;<br />
            SqlDataReader reader = null;<br />
            reader = cmd.ExecuteReader();<br />
            while (reader.Read())<br />
            {<br />
                MessageBox.Show(reader["user_name"].ToString() + reader["user_pass"].ToString());<br />
                if (text_user.Text == (reader["user_name"].ToString()) && text_pass.Text == (reader["user_pass"].ToString()))<br />
                {<br />
                    MessageBox.Show("Loged In");<br />
                }<br />
                else MessageBox.Show("Failed to Login");<br />
            }<br />
        }<br />
<br />
   }<br />
}<br />