After trying to design my own inventory app, I decide to subscribe to memento database, and wrote my app to invoke thermal printer.

When designing the app, flexibility is the main issue. I designed a dedicated attribute table for max flexibility, but when come to search those attributes, it's really hard to considering all different data types. All attributes are stored in string, but not all attributes are natural to be a string.

For example, the date, it can be represented into string, but people don't have a standard way to describe date in string, thus really hard to search.

And considering I may have other datas to organise, subscribe to memento database might not ne a bad decision.