title: Mysql : table strucutre design for post 'like' and 'unlike'
body: <p>I have an android app which a user can <code>"like/unlike"</code> a post,</p>
  
  <p>I have created a table:</p>
  
  <pre><code>| id | post_id | user_id |
  |  1 |     105 |      67 |
  |  2 |      76 |      56 |
  |  3 |      36 |     102 |
  </code></pre>
  
  <p>with id auto-increment, is this table structure correct?</p>
  
  <p>since one person can like/dislike multiple times, do you think deleting the row (unlike) + create new row (like) is good practice?</p>
  
  <p>The auto-increment row will increase and reached big numbers if there are many users, is this bad? since the auto-increment cannot reuse the deleted row.</p>
  
  <p>if I added an extra <code>boolean</code> column, <code>like</code> with value <code>1</code> or <code>0</code></p>
  
  <p>and consider a user without an existing row in the table + 
  user with an existing row but column <code>like = 0</code> as unlike</p>
  
  <p>will that be better?</p>