find 8-digit named SQLite databases under current directory and run SQL and redirect the result to individual files. The gist demonstrates the use of regex in find command.

list_dates.sh

for db in $(find . -regextype posix-extended -regex '.*\<[0-9]{8}$' | cut -d'/' -f2-)
do
    cat << EOF | sqlite3 $db > $db.dates
select distinct date(login_time, 'unixepoch') login
  from login_record
;
EOF
done

The [0-9] is used instead of \d because \d is not supported by find. The -regextype posix-extended is also required as the repetition modified {8} is an extended feature which is enabled by default.