Complex sentence: Several appearances singing and doing comedy skits with Frank Sinatra on the CBS-TV Frank Sinatra Show soon followed, then Columbia Records and the song "I Saw Mommy Kissing Santa Claus," recorded when he was 12 years and 11 months old.
Split into simpler sentences: Several appearances singing and doing comedy skits with Frank Sinatra on CBS-TV's "Frank Sinatra Show" soon followed. Then he recorded the song I Saw Mommy Kissing Santa Claus for Columbia Records, when he was 12 years and 11 months old.