php - How to make conditions with CASE WHEN in SphinxQL? -

How can I set the condition for a spinks search? In my custom MySQL code, as follows:

How can I re-code it as a Spinks search?

  $ condition = "(in case related_type = 'course' THEN related_ id = 1 ELSE related_id IN (2, 3,4) END)"; << Code>   
 
 
 There is a  IF ()  function in SPINXQUL Used in the same fashion 
 
 For example: 
 
  SELECT *, IF (related_type = 'course', related_id = 1, IN (related_id, 2,3) , 4)) as filter from myindex where the filter = 1  
 
 should be in the  SELECT  section, not in  WHERE  
 
 (Note also a slightly different syntax for  IN .) This function is in Sphinx