I need to find what the date is X% between two date fields. The use case is I want to send an email to someone who is 70% of the way through their tenancy.

For example,

Move-in date = 01/01/20
Move-out date = 31/01/20
Reminder date (70%) = 22/01/20

Is there a simple way to do this within one SQL? From what I've found so far, it's possible to find the percentage, but not the date it equates to.


You can do this using the functions DateAdd, DateDiff and a multiplication. The query could look like this:

  DateAdd(day, DateDiff(day, movein, moveout)*0.7, movein) as [reminder_date]

For your example this results in the date 2020-01-22.

Further resources:

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