select nb, referer,
  case when referer ~ 'http://\\w+\.google\.*?q=(\.*?)' then regexp_replace(referer, 'http://\\w+\.google\.*?q=(\.*?)', '\\1', 'g')
    else regexp_replace(referer, 'http://\\w+\.yahoo\.*?p=(\.*?)', '\\1', 'g')
  end as query
from stats_day_ref
where idblog=2
and (
referer ~ 'http://\\w+\.google\.*?q=(\.*?)'
OR
referer ~ 'http://\\w+\.yahoo\.*?p=(\.*?)'
);