LibreOffice includes Base which is a full database management program complete with GUI capabilities and the full HSL relational database. From the blurb:
"LibreOffice Base provides wizards to help users who are new to database design (or just new to the software) to create tables, queries, forms and reports, and it comes supplied with a set of pre-defined table definitions for tracking assets, customers, sales orders, invoices and many other common and useful items."
LibreOffice is Free, Gatis & Open Source, will run on multiple operating systems, is available as a portable installation, (take it with you on a USB key), supports multiple localisations (possibly more than just about anything else that I have come across).