I remembered Dan working on this project many years ago. The key idea is to create hierarchies in SQL without having to do self joins. This can be useful for co

I remembered Dan working on this project many years ago. The key idea is to create hierarchies in SQL without having to do self joins. This can be useful for computing permissions quickly, for instance, a department manager may have permissions for his/her department, while someone working under the manager would have a subset of his permissions. One of the problems encountered is there is a limit to how deep the hierarchy can be, and the modelling limitations of mapping permissions to an org chart.