http://forums.oracle.com/fo... select to_char( date '2008-01-04', 'IW' ) from dual Basically, there are 3 to_char format models to get week number: * W - week number in a month * WW - week number in a year, week 1 starts at 1st of Jan * IW - week number in a year, according to ISO standard - alternative: ROUND(TO_NUMBER(TO_CHAR(dat... ......