title: Add more than one data in a field in SQL
body: <p>I have a table named 'users' . In 'users' table, contains a field named 'chapter_id' . 
  Another table named 'chapters' contains all the name of the chapters of a particular subject with respect to their id. I want to add more than one 'id' from 'chapters' to 'chapter_id' in users. 
  I am able to add one 'chapter_id' in 'users' from 'chapters'.
  Here is my users table :</p>
  
  <pre><code>-------------------------
  id | name | chapter_id  |
  -------------------------
  1  | ABC  |    8        |
  -------------------------
  </code></pre>
  
  <hr>
  
  <p>Here is my 'chaprers' table:</p>
  
  <pre><code>-------------------------
  id | name |   subject   |
  -------------------------
  1  | XYZ  |   PQR       |
  -------------------------
  </code></pre>
  
  <hr>
  
  <p>The query that I used to select the name from 'chapters' where 'id' = 'some id' in table 'users' is :</p>
  
  <pre><code>SELECT `name`, subject FROM chapters WHERE id = (SELECT chapter_id FROM users where id= 11)
  </code></pre>
  
  <p>And to insert the chapter_id, I wrote : </p>
  
  <pre><code>UPDATE `users` SET `chapter_id`= (SELECT id FROM chapters WHERE id = 5) WHERE id =11
  </code></pre>
  
  <p>Now I want to add more than one 'id' in 'chapter_id' ! What is the query to do that? </p>