title: Mysql: Can't use a subquery field as a condition?
body: <p>This code runs fine. Pay special attention to the 'AS commercial' subquery field. It works.</p>
  
  <pre>
  SELECT `Contacts`.`id`,
      (
          SELECT `team_members`.`id`
          FROM team_members
          INNER JOIN team_categories_team_members AS memcat
              ON `team_members`.`id` = `memcat`.`team_member_id`
          WHERE `memcat`.`team_category_id` =3
      ) AS commercial
      FROM `oys001`.`team_members` AS `Contacts`
      JOIN `oys001`.`brands_team_members` AS `BrandsTeamMember` ON ( 
          `BrandsTeamMember`.`brand_id` =2
          AND `BrandsTeamMember`.`team_member_id` = `Contacts`.`id` )
  </pre>
  
  <p>However, now I want to perform a condition on it, so I just add this:</p>
  
  <pre>
   WHERE commercial > 0
  </pre>
  
  <p>And it tells me the field does not exist... What's going wrong here?</p>