SqlConnection con = new SqlConnection(@"Data Source=(LocalDB)v11.0;Integrated Security=True;AttachDbFilename=c:usersnamedocumentsvisual studio 2013ProjectsDBSampleDBSampleDatabase1.mdf");
SqlCommand cmd = new SqlCommand("Select * From Account", con);
SqlDataReader rd= cmd.ExecuteReader(); ;

SqlConnection con = new SqlConnection(@"Data Source=(LocalDB)v11.0;Integrated Security=True;AttachDbFilename=c:usersnamedocumentsvisual studio 2013ProjectsDBSampleDBSampleDatabase1.mdf");
SqlCommand cmd = new SqlCommand("Select * From Account", con);
con.Open();
SqlDataReader rd= cmd.ExecuteReader();

using (SqlConnection con = new SqlConnection(@"Data Source=(LocalDB)v11.0;Integrated Security=True;AttachDbFilename=c:usersnamedocumentsvisual studio 2013ProjectsDBSampleDBSampleDatabase1.mdf"))
{
    using (SqlCommand cmd = new SqlCommand("Select * From Account", con))
    {
        // here the connection opens
        con.Open();

        using (SqlDataReader rd = cmd.ExecuteReader())
        {
            // do your data reading here
        }
    }
}