How to make automatic upgrade script for module

There is a prepared zip package with the simplest update for Dolphin 7 module [here]. Download it, unpack and upload to the modules/me/bloggie/updates/ folder. bloggie folder is the root folder of Bloggie module which was described ​here, updates folder is a folder for all updates for Bloggie module, if it doesn't exist then you need to create it.

The zip package contains update_100_110 folder. It is up to you how to name the folder but it is a good practice to include "version from" and "version to" into the folder name, it is just more clear. Lets describe each file in the update. This is almost the minimal set of files for the module's update:

bloggie/updates/update_100_110/install/
Update installation directory, where all installation files are located, like SQL files and language files.
bloggie/updates/update_100_110/install/config.php
Update installation config file. We will take a closer look at this later.
bloggie/updates/update_100_110/install/installer.php
Update installer class. You can add some custom installation scripts and override default behaviour.
bloggie/updates/update_100_110/install/info
Installation information messages folder. If you need to display information messages upon update install, you will need to place files here - also special instructions are needed to point to in the install config file to display these messages properly.
bloggie/updates/update_100_110/install/langs
Update languages must be located in this dir. The language file must be a php file with the name of two letters of the language code. We will take a closer look at an example of the language file later.
bloggie/updates/update_100_110/install/langs/en.php
An update for default English language file.
bloggie/updates/update_100_110/install/sql
SQL script for update install is here.
bloggie/updates/update_100_110/install/sql/install.sql
Update installation SQL file.
bloggie/updates/update_100_110/source
A folder with files and folders which should be uploaded in module's folder. So, files and folders structure should match module's one. You may read more about module's file structure ​here.