Download
http://www.mediafire.com/file/qpiuiq0sc ... e.zip/file
Extract it to a "trusted directory" according to Tools>Options...Security>[Macro Security]>Trusted Sources
Open the database document. The embedded macro will connect the document to the database folder using the hsquldb.jar in the driver folder.
It is just a small demo for the built-in DATEADD function shipped with HSQL2 which calculates dates, times and timestamps from a date and a number.
The status bar indicates that the connected HSQL database resides outside the document.
The table designer has limited access to the underlying table structures. LibreOffice 6 allows me to add columns and edit relations but I can't edit existing columns. With menu:Tools>SQL... I have full control over the database because it allows me to talk directly to the underlying database engine. I could also use more advanced development tools since the stand-alone database is editable with any software that can handle JDBC databases.
This external database is by far more secure than the embedded one.
This external database can be run in server mode providing multi-user access. I run such a HSQL server since 9 years with zero problems.
This external database can be used online and offline with any tool set able to query data from a JDBC database.
The Open/LibreOffice database user won't notice any difference. Forms, reports, office documents work as expected with this database, just like they would with a MySQL database or something else.