You can use a relatively new feature of MySQL to do this (no perl needed):

SELECT ssn FROM ssn_table ORDER BY RAND LIMIT 3
[download]

That is, the ordering by RAND is the trick. I forget which version of MySQL introduces it, but if you don't have it, the other suggestions presented are a bit more portable.

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Dr. Michael K. Neylon - mneylon-pm@masemware.com || "You've left the lens cap of your mind on again, Pinky" - The Brain