C#中怎么取到当前日期是在一年中的第几周

C#中怎么取到当前日期是在一年中的第几周
private int WeekOfYear(string date)
{
DateTime curDay = Convert.ToDateTime(date);
int firstdayofweek = Convert.ToInt32(Convert.ToDateTime(curDay.Year.ToString() + "-" + "1-1").DayOfWeek);
int days = curDay.DayOfYear;
int daysOutOneWeek = days - (7 - firstdayofweek);
if (daysOutOneWeek <= 0)
{
return 1;
}
else
{
int weeks = daysOutOneWeek / 7;
if (daysOutOneWeek % 7 != 0)
weeks ++;
return weeks + 1;
}
}
或
select datepart(week,getdate())