MyVideos database: new "Has Subtitles" Column

Is it possible to do something to update the MyVideos*.db, Episode table and use one of the columns to create YES/NO value to indicate that episode/movie has subtitle? And then use this to show a tag at the skin showing that the episode/movie has subtitles.

Check if file exists using "Select replace(c18,'.avi', '.srt') from episode" and update for example the colum c20 or c21 .... c23 (one that is empty)

thanks