Question

Sir,
I am having some problem regarding database in SQL Server.
My project is desktop application with login method….
My program is written in C# executes normally as I want with no errors in my queries…
But data is not stored back to database which the program inserts or updates… My database is created by visual studio 2010 as a separate mdf file in data folder…
So kindly please help me in this. Here is a sample code :

private void btnLogin_Click(object sender, EventArgs e)
{
  try
  {
     using (SqlConnection cn = new SqlConnection("Data Source=.\\SQLEXPRESS;AttachDbFilename=|DataDirectory|\\Database_File.mdf;Integrated Security=True;User Instance=True"))
     {
        using (SqlCommand cmd = new SqlCommand("select * from table_users where user_name='" + txtBoxUserName.Text + "' and user_password='" + txtBoxUserPass.Text + "' ",cn))
        {
          cn.Open();                        
          dr = cmd.ExecuteReader();
          while (dr.Read())
          {
            if (dr["user_name"].ToString() == txtBoxUserName.Text && dr["user_password"].ToString() == txtBoxUserPass.Text)
            {
              ...
              ...
              try
              {
                using (SqlCommand cmd1 = new SqlCommand("insert into table_user(id,user_name,user_status) values(" + key + "," + active_user_name + "',"+ user_status + ")",cn))
                {
                  cmd1.ExecuteNonQuery();
                  Thread form_name = new Thread(new ThreadStart(thread_Proc_form_name));
                  form_name.Start();
                }
              }
              catch  { throw;}
            }
          }
        }
     }
  }
  catch  { throw;}
}

The program runs as i want but when i look into the database table no changes are saved. For eg : when I login then no information of login is shown in the database on next run..
Same is the case for register… every time i run the app I have to register again and again. I don’t know where is the error. Please help me sir where i am going wrong….

Thanks & Regards
Saurabh Mahajan

Answer 1

This snippet suggests to me that you’ve got a Database_File.mdf in your solution in Visual Studio:

AttachDbFilename=|DataDirectory|\\Database_File.mdf 

Each time you build your project, Database_File.mdf will be copied to the output directory, overwriting whatever file was there previously.

This behaviour is by design.

Note that user instances are deprecated, you should consider attaching your Database_File.mdf to your SQL Express instance for the duration of development or using something like SQL Server LocalDB.