2015年2月19日 · IYYY format uses the ISO standard and IW returns the week of the year from 1 to 53 based on the ISO, while WW returns a value between 1 and 52 (see Format Models from the Oracle Docs reference). They are similar to what you can achieve using Week() and YearWeek() in QlikView ( Redefining the Week Numbers by Henric Cronström is a must)