Query: calculating the hour, on the hour

I need a query that returns the previous hour, on the hour.

Select to_char(to_char(sysdate, 'HH24')-1) from dual;

This query returns '7', but I need a query that will always return 2 characters ('07') and also will return '23' when it is midnight.

Thanks for any help,
JB

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Before you buy. Received on Mon Oct 11 1999 - 10:47:56 CDT