title: An unhandled exception of type 'System.Data.SqlClient.SqlException' occurred in System.Data.dll in VS
body: <p>I'm having this problem I have to solve it by monday (I'm new to C# and VS)
  so this is my code:</p>
  
  <pre><code>public partial class Add_Delete_Domain : Form
      SqlCommand cmd;
      SqlConnection con;
      SqlDataAdapter da;
  
  
      public Add_Delete_Domain()
      {
          InitializeComponent();
      }
  
      private void radioButton1_CheckedChanged(object sender, EventArgs e)
      {
  
      }
  
      private void button1_Click(object sender, EventArgs e)
      {
          con = new SqlConnection(@"Data Source=(LocalDB)\v11.0;AttachDbFilename=" + @"C:\Users\Avi\Documents\Visual Studio 2015\Projects\FriendsProject1\FriendsAdminForm\FriendsDB.mdf;Integrated Security=True");
          con.Open();
  </code></pre>
  
  <p>as you can see im just trying to open the DB and im getting this error message</p>
  
  <p>BTW the line of code above looks like this after i took the code from someone else and putted my DB path.
  when im taking my connection string from the DB properties all the ling of code is errors/ this is what happen when i take my connection string:</p>
  
  <p><img src="https://i.stack.imgur.com/boUk8.jpg" alt="enter image description here"></p>
  
  <p><img src="https://i.stack.imgur.com/DBlHw.jpg" alt="enter image description here"></p>