date to unix seconds

[robert.e.o'brien]

I get data from a database that I want to do some statistical
analysis on.  Part of the data is a date in typical  mm/dd/yy
format.  I want to convert this to a number.  Unix seconds is fine
since this data doesn't go back further than 1989.  I looked at the
Unix "date" command and it talked about superusers using the date
command to set the time on the machine in Unix seconds.  Also about
getting the current back out in a variety of formats.  I couldn't 
find the program where you put in a data and get out seconds.
Give that I get the program that goes from date to seconds, I'd
also like a program that goes the other way.  Thanks.

Bob O'Brien