help with my sql

I have two tables.
table A has a date column, and a date_key, table B has a year(varchar2) , month(varchar2) , day(varchar2), hour(varchar2),minute(varchar2) column, and a date_key

I need to do something like this

update table A
set A.date_key = B.date_key
where
B.year = to_char(A.date,'yyyy')

and B.month = to_char(A.date,'mm')
and B.day = to_char(A.date,'dd')
and B.hour = to_char(A.date,'hh24')
and B.minute = to_char(A.date,'mi')

How could I do that?

Thanks for your help Received on Wed Aug 21 2002 - 19:03:20 CDT