title: Drupal database API query - row.update if exists, else row.insert
body: <p>I've been trying to run a query in drupal that'll update entries if they already exists or insert a new entry if it doesnt. The code looks like this at the moment:</p>
  
  <pre><code>db_query("IF EXISTS (SELECT %d FROM {uc_posten_packages.pid})
  UPDATE {uc_posten_packages} SET title = '%s', label = '%s', cost = '%d', length = '%d', width ='%d', height = '%d', weight = '%d'  WHERE pid = %d
  ELSE
  INSERT INTO {uc_posten_packages} VALUES ('%d', '%s', '%s', '%d', '%d', '%d', '%d', '%d')",$id, $title, $label, $rate, $length, $width, $height, $weight, $id, $id, $title, $label, $rate, $length, $width, $height, $weight);
  </code></pre>
  
  <p>I can't see why that query throws me an error. All the numbers in the error are correct</p>
  
  <pre><code>...near 'IF EXISTS (SELECT 1 FROM uc_posten_packages.pid) UPDATE uc_posten_packages ' at line 1 query:
  IF EXISTS (SELECT 1 FROM uc_posten_packages.pid) UPDATE uc_posten_packages SET title = 'vfbv', label = 'bbv', cost = '22', length = '232', width ='22', height = '22', weight = '22' WHERE pid = 1 ELSE INSERT INTO uc_posten_packages VALUES ('1', 'vfbv', 'bbv', '22', '232', '22', '22', '22')
  </code></pre>
  
  <p>Should this query work and/or is there some better way dealing with this in drupal?</p>