either use a lookup to a calenderfile to fetch the weeknumber on a date, or calculate the weeknumber using the day of the year format like:
TO_DATE(DATE,'DDD')
This should fetch you an integer between 1 and 366 which you can recalculate to a weeknumber (with week 1 starting on the first day of the year)
T. Blom
Information analyst
tbl@shimano-eu.com