基于可变开始日期 + 天数间隔，我需要找到当天之后的下一个日期

Question

I have an Anchor Date, eg. 01-01-2020, which is a variable. I also have a days interval, eg. 7 days, which is also a variable. I need to get the next date on or after the current date which is a whole number of intervals after the anchor date.

It's 01-16-2020 right now. The date I would expect is 01-22-2020.

The result date will be within a SELECT Statement as a column. The select statement provides the variables.

Answer 1

Consider:

dateadd(
    day,
    7 - datediff(day, '2020-01-01', cast(getdate() as date)) % 7,
    cast(getdate() as date)
)

Where the anchor date is '2020-01-01' and 7 is the interval.

This works by taking the days difference between the current date and the anchor: for today 2020-01-16, result is 15. Then we get the modulo 7 of this value (which is 1), and substract it from 7 (gives 6), which gives us the number of days that we need to add to the current date to get the expected value (2020-01-22).

Demo on DB Fiddle