Of course, the real solution is to let the DB do the work: 

SELECT stamp,
       COUNT(*)
  FROM Table
 WHERE state = "In Use"
 GROUP BY stamp

[download]

I think that won't give stamps with zero "In Use". I think you'll need a subquery if you want that result.

In reply to Re: Creating a hash of arrays from DB results (db) by ikegami
in thread Creating a hash of arrays from DB results by blaze

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