invalid number error

        it's been a while since i've done any sql, but i'm having some trouble with what really shouldn't be a complicated select statement at all. the error i get (ORA-01722: invalid number) seems to be based on this part of the where clause:

where mac.contract_number=cct.contract_code

   and to_number(mac.create_date) > (select (to_char(sysdate,'J') - to_char(to_date('1/2/70','MM/DD/YY'),'J'))*86400 from dual)

        create_date is a number field in the table aliased to mac in the from statement (not shown), which contains a value corresponding to the number of seconds since jan. 1, 1970 (as created by a different app; i don't like it, myself, but can't do anything to change it). i'm trying to have the select match all items in the two joined tables (mac and cct) that are newer than one day old. the nested select after the greater-than sign works fine if run on its own, returning the number of seconds from jan. 1, 1970 until midnight of the day before the statement is run, and a select of to_number(mac.create_date) works fine as well (the to_number is redundant, i realize, since create_date is already a number field, but i put it in after i got the error, just to be safe).

        i'm sure it's something simple that i'm forgetting here; could some kind soul point it out to me?

	relearning sql,
	sweth.

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