How to get data from period - this month

[sculptorlv]

Hello! Hope for your help again.

I have columns "Posting_date" and "Sales".

How can I get all "Sales" values from current month?

I need to replace IF value "Bouth__PostingDate > Today()- 15" in the following sentence :

= SUM(   IF(PostingDate > Today()- 15, Sales, 0) )

Because - 15 is ok only, if we have 15.12.2015 date today. How can I make it ok for all TODAY dates?

Thank you in advance.

[sculptorlv]

Find answer for my additional question.

I used this function:

=sum(

IF(InMonth(Bouth__PostingDate,Today(),0),Bouth_Cofee_Item_Money,0)) for this month

IF(InMonth(Bouth__PostingDate,Today(),-1),Bouth_Cofee_Item_Money,0)) for previous month

IF(InMonth(Bouth__PostingDate,Today(),-2),Bouth_Cofee_Item_Money,0)) for ex previous month etc.

[Anonymous]

if you want to subtract month then do like this:

Assume DateField is having Today's date

=addmonths(month(DateField), -1)    //would return November month

=addmonths(month(DateField), -2)    //would return October month

=addmonths(month(DateField), -3)    //would return September month

and so on...

[sculptorlv]

OMG!! So simple.. got stupid!

Thank you.