How to find hook_update_N, current N value

To find it via drush, run this command 

drush php:eval "echo drupal_get_installed_schema_version('modul_name');"

also if you want to look it up with some DB admin tool, look under table `key_value`,  `system.schema` collection row, with a `name` of your module and you will get value of last run update.

Dumping and exporting DB with drush and piping to ZIP

If you want to import DB that is in ZIP format with one line

gunzip -c my_db.sql.gz | drush sqlc

to dump DB to ZIP file write this

drush sql-dump --gzip --result-file=my_db.sql

you will end up with my_db.sql.gz file.