title: Should I use AI on these fields in MySQL?
body: <p>I have this db below. I wonder how I should use the ID to identify each record.
  Everything is connected from the <code>classified_table</code>!
  Two Questions: <br></p>
  
  <p>Should I use AI on every PK in this case?</p>
  
  <p>Could somebody give me the FULL code for selecting an entire classified from only an <code>ad_id</code> ("bmw_330ci_8939483" for example)?</p>
  
  <p>I am new to normalized db and making a good database work, so detailed instructions is very much appreciated... Also if you notice any 'wrongs' in this db please let me know.</p>
  
  <pre><code>category table:
  cat_id (PK)
  cat_name
  
  category_options table:
  option_id (PK)
  cat_id (FK)
  option_name
  
  option_values table:
  value_id (PK)
  option_id (FK)
  value
  
  classifieds table:
  classified_id (PK)
  ad_id (VARCHAR) something like "Bmw330ci_28238239832" which will appear in URL
  poster_id (FK)
  cat_id (FK)
  area_id (FK)
  headline
  description
  price
  etc....
  
  posters table:
  poster_id (PK)
  name 
  email
  tel
  password
  
  area table:
  area_id (PK)
  area
  community
  </code></pre>
  
  <p>Thanks</p>