How to update an SQLite database with a search and replace query?

You are probably looking for the replace function.

For example,

update table_name set 
  content_url = replace(content_url, 'band%20albums', 'bands/studio%20albums')
where
  content_url like '%nazgulled/music/band_20albums/%';

More documentation at http://sqlite.org/lang_corefunc.html