[help] Details about the table DATABASECHANGELOG

+---------------+
| Field         |
+---------------+
| ID            |
| AUTHOR        |
| FILENAME      |
| DATEEXECUTED  |
| ORDEREXECUTED |
| EXECTYPE      |
| MD5SUM        |
| DESCRIPTION   |
| COMMENTS      |
| TAG           |
| LIQUIBASE     |
| CONTEXTS      |
| LABELS        |
| DEPLOYMENT_ID |
+---------------+

1.) When is this table populated?
2.) How are the fields populated?

It's a Liquibase database table. If you want to know more about it, you should check Liquibase project:

http://www.liquibase.org/