title: Mysql Results from one table that hasn't been populated in another
body: <p>I would like to get all the results from 1 table that havent been populated in another is this possible in a query? I have been trying with a Left join but with no avail.</p>
  
  <p>Table1: users_postcodes
  Field: postcode</p>
  
  <p>Table2: postcodes
  Field: postcode</p>
  
  <p>I want to get all the postcodes from table2 which haven't been added to table1.</p>
  
  <p>This is what I have so far, I know for a fact its wrong, but any help would be very helpful:</p>
  
  <pre><code>SELECT t1.*, 
  t2.`postcode` AS `nouser_postcode` 
  FROM `postcodes` AS t1 
  LEFT JOIN `users_postcodes` AS t2 on t2.`postcode` != t1.`postcode`
  </code></pre>