title: How to do select from where x is equal to multiple values?
body: <p>I am debugging some code and have encountered the following SQL query (simplified version):</p>
  
  <pre><code>SELECT ads.*, location.county 
  FROM ads
  LEFT JOIN location ON location.county = ads.county_id
  WHERE ads.published = 1 
  AND ads.type = 13
  AND ads.county_id = 2
  OR ads.county_id = 5
  OR ads.county_id = 7
  OR ads.county_id = 9
  </code></pre>
  
  <p>I'm getting very strange results from the query and I think its because the first OR is negating the AND operators that are found before it.</p>
  
  <p>This results in getting results back for ads of all types and not just for the type 13. </p>
  
  <p>Each time the query is called there may be a differnt amount of county entities that need to be looked up.</p>
  
  <p>Any help on the correct way to go about this would be appreciated.  </p>