CREATE TABLE persons (name CHAR(50) PRIMARY KEY, company char(50) references companies.name);
CREATE TABLE companies (name CHAR(50) PRIMARY KEY, business char(50));

##</code><code>##

> cd db
> ls
persons
companies
> ls persons
Fergal Daly
Bill O'Brien
> cd "persons/Fergal Daly"
> ls
name
company
company:row
> cat company
Blogtronic
> ls -l company:row
cmopany:row -> ../../companies/Blogtronic
> ls company:row
name
business
> cat company:row/business
Maker of electric lawnmowers and dangerous toys

##</code><code>##

> cd companies/Blogtronic
> ls
name
business
:referers
> ls :referers
persons
> ls referers/persons
company
> ls referers/persons/company
Fergal Daly
... other rows of persons who's company field references Blogtronic's primary key