【VB.NET】 週番号の取得
■DatePart(DateInterval,Date,FirstDayOfWeek)
DateInterval列挙
DateInterval.Day
DateInterval.DayOfYear
DateInterval.Hour
DateInterval.Minute
DateInterval.Month
DateInterval.Quarter
DateInterval.Second
DateInterval.Weekday
DateInterval.WeekOfYear
DateInterval.Year
FirstDayOfWeek列挙
FirstDayOfWeek.Friday
FirstDayOfWeek.Monday
FirstDayOfWeek.Saturday
FirstDayOfWeek.Sunday
FirstDayOfWeek.System
FirstDayOfWeek.Thursday
FirstDayOfWeek.Tuesday
FirstDayOfWeek.Tuesday
■例
指定した日付の週番号を取得（週の開始を月曜日で指定）
DatePart(DateInterval.WeekOfYear, 日付, FirstDayOfWeek.Monday)