php - Cant retrieve user info from database when running query, codeigniter -

I am having a problem, it should be very simple, but I can not seem to fix it. I am trying to capture the user's user ID by searching for the username in the database. But I am just getting a zero value .. Please tell me what I am doing wrong.

Here is the code for the query:

  private function get_u_id ($ user) {$ sql = "SELECT * user WHERE 'user name' =?"; $ Query = $ this- & gt; Db- & gt; Query ($ sql, array ($ user)); Forex Currency ($ query-> Result As Row) {return line $ ['id']; }}   
 I am storing this information in one session, so this code is:  
  $ user_session_data = array ('user' = & $ P_info ['username'], 'email' = & gt; $ this- & gt; get_user_email ($ p_info ['username']), 'u_id' => $ this- & gt; get_u_id ($ P_info ['username'], 'valid' = & gt; TRUE); // Set a session, (username, email, user_id) private function set_ession ($ user_data) {$ this- & gt; Session-> Set_user data ($ user_data); }   
 And when I use this session print_r () it looks like this  
  [user_data] = & gt; [User] = & gt; Wilprim [email] = & gt; [U_id] = & gt; [Valid] = & gt; You got incorrect citations in the query:  
 
 
 
  
 
 $ sql = "Choose * from users where 'username' =?"; ^ - ^ -   
  'username'  is a  STRING , not field name  Username  is also not a reserved word, so there is no need to quote it anyway.  
 Any of the user:  
  $ sql = "Select * from users where 'username' =? '; // note brackets $ sql =" select * In the written form, your query will return any data, if you had a user whose username was literally By format  username was .