I want to order search results by (age group, rank), and have age groups of 1 day, 1 week, 1 month, 6 months etc. I know I can get the "days old" with

```
SELECT NOW()::DATE - created_at::DATE FROM blah

```

and am thinking to do a CASE statement based on that, but am I barking up the right tree performance wise?﻿ Is there a nicer way?