> How do I filter/sort contacts by the 'State' condition in the State library?
// Assumes link to city in Contacts is City and link to state in Cities is State
Now, you have a field in Contacts using which you can sort, filter, and group.
First, I've been almost entirely unable over the years to have a rational conversation about relational database theory with anyone. Everyone comes from a different walk of life, with different models and success stories in their minds, and they all tend to be very religious about it. So, I'll say that it's pretty damned relational, that Oracle, DB2, Sybase, etc each have their quirks underneath the relational mantle. However, though there could be, there is no SQL engine within or over the top of Memento, and many folks use things in Memento that go beyond relational, like many-to-many links.
Anyway, underneath, there is a relational engine that uses IDs for physical storage, but the real answer is that at the logical level, a link is to an "entry name", which is built from the field role set on defined fields. An entry name is quite like a primary key, and one can set a library to enforce uniqueness of entry names, which enables relational features. It does no "storing" like you suggest.
...It does no "storing" like you suggest...
Again, a huge thanks for your time!