as long as vs if only

as long as

conj
  • Used other than figuratively or idiomatically: see as, long. 

  • Provided that, if, assuming (depending upon some condition or requirement). 

  • While, Since 

if only

conj
  • Used other than figuratively or idiomatically: see if, only. 

  • I wish that; signifies a wish or desire for the present or the future. 

  • I wish that; signifies a regret about an action in the past. 

  • Even if for no other reason than; only just. 

How often have the words as long as and if only occurred in a corpus of books? (source: Google Ngram Viewer )