# Thread: Date Formula Support Needed Thanks: 0 Likes: 0

1. ## Date Formula Support Needed

Good afternoon all,
I'm looking for some help with a BI Power Query formula (Trying to cut out lots of manual work) that will take a date from a column (So 10/07/2019) and return back whether that date was Last Week, Last Week -1, Last Week -2, etc up to Last Week -4 in a new column to the right of the date

Any help or support would be incredible

2. ## Re: Date Formula Support Needed

what does that mean: Last Week -1? Last Week - one day? - one week?

anyway try:

Code:
`= if Date.IsInPreviousNWeeks(Date.AddDays([Date],0),1) = true then 1 else if Date.IsInPreviousNWeeks(Date.AddDays([Date],7),1) = true then 2 else if Date.IsInPreviousNWeeks(Date.AddDays([Date],14),1) = true then 3 else if Date.IsInPreviousNWeeks(Date.AddDays([Date],21),1) = true then 4 else null`
it will give you a week number if date is in previous week (1), previous previous week (2), previous previous previous week (3) or previous previous previous previous week (4) else null

 Date Date NthWeek 10/07/2019 10/07/2019 1 02/07/2019 02/07/2019 2 25/06/2019 25/06/2019 3 18/06/2019 18/06/2019 4 10/06/2019 10/06/2019 18/07/2019 18/07/2019 03/07/2019 03/07/2019 2

3. ## Re: Date Formula Support Needed

Hi mate,

This is brilliant thank you. All I meant was any dates from the previous week I want to be able to show LW, any dates from the week before that date would be LW-1 (Last week -1) and so on

I have loads of sales data by day but want to show some graphs to compare weekly data and in Excel i use LW, LW-1, LW-2, LW-3, LW-1 instead of lets say Week 36, Week 35, Week 34, Week 33, Week 32

Cheers
Steve

4. ## Re: Date Formula Support Needed

So managed to change the 'then 1' to 'then "LW" and it worked a treat!!

How would the same priniples work if i was just looking at weekend performance? How could i show if a date was lets say between Friday - Sunday lastweek then return a 1, Friday - Sunday the week before would be 2 etc etc?

Any thoughts?

Cheers
Steve

5. ## Re: Date Formula Support Needed

there are more function like:

• Date.IsInPreviousDay
• Date.IsInPreviousMonth
• Date.IsInPreviousNDays
• Date.IsInPreviousNMonths
• Date.IsInPreviousNQuarters
• Date.IsInPreviousNWeeks
• Date.IsInPreviousNYears
• Date.IsInPreviousQuarter
• Date.IsInPreviousWeek
• Date.IsInPreviousYear

etc...