How to calculate monthly and quaterly LAG periods in PROC SQL ?

[emrancaan]

I'm just wondering how to calculate the lag dates for previous month and previous quarter in Proc SQL. I'm using following proc sql but I cannot generate the lag period for each period.

proc sql;
CREATE TABLE periods_eba as

Select  distinct
CASE WHEN  calendar_day > &qtrly_cutoff_date
	 THEN  'Monthly' ELSE 'Quarterly' END AS Rep_Period,
intnx('month',calendar_day,0,'beginning')  as period format=mmyyd7.,

CASE WHEN calendar_day > &qtrly_cutoff_date
	 THEN intnx('month',calendar_day,0,'beginning') 
	 ELSE intnx('qtr',calendar_day,0,'beginning') END as periodBeg format=yymmdd10., 
    
intnx('month',calendar_day,0,'end')  as periodEnd format=yymmdd10.
from ebaperiod
Order by lagperiod desc
;QUIT;

My intention is to create 

1) From Today till May 2017  monthly periods

2) From May 2017 to Jan2010 Quarterly periods

final data set will contain lag periods ..and it will look like similar to below.

Rep_Period	lagperiod	lagperiodBeg	lagperiodEnd	period	periodBeg	periodEnd
Monthly	02-2018	2018-02-01	2018-02-28	03-2018	2018-03-01	2018-03-31
Monthly	01-2018	2018-01-01	2018-01-31	02-2018	2018-02-01	2018-02-28

Or more precisely

Rep_Period	lagperiod	lagperiodBeg	lagperiodEnd	period	periodBeg	periodEnd
Monthly	02-2018	2018-02-01	2018-02-28	03-2018	2018-03-01	2018-03-31
Monthly	01-2018	2018-01-01	2018-01-31	02-2018	2018-02-01	2018-02-28
Monthly	05-2017	2017-05-01	2017-05-31	06-2017	2017-06-01	2017-06-30
Quarterly	03-2017	2017-01-01	2017-03-31	05-2017	2017-05-01	2017-05-31
Quarterly	12-2016	2016-10-01	2016-12-31	03-2017	2017-01-01	2017-03-31

[ChrisNZ]

Your SQL looks fine, What is the issue?

[emrancaan]

I want to genarate three columns 2,3,4 having lag periods

[ChrisNZ]

I am unsure why you can't do it. Like this?

proc sql;
  create table PERIODS_EBA as
  select  distinct
    ifc(CALENDAR_DAY > &qtrly_cutoff_date., 'Monthly', 'Quarterly') as REP_PERIOD length=9
   ,intnx('month',calendar_day,0 ,'beginning')                      as PERIOD     format=mmyyd7.
   ,intnx('month',calendar_day,-1,'beginning')                      as LAGPERIOD  format=mmyyd7.
        
   ,intnx(ifc(CALENDAR_DAY > &qtrly_cutoff_date.,'month','qtr')
         ,CALENDAR_DAY,0,'beginning')                               as PERIODBEG  format=yymmdd10.
        
   ,intnx('month',CALENDAR_DAY,0,'end')                             as PERIODEND  format=yymmdd10.
  from EBAPERIOD
  ;
quit;

REP_PERIOD	PERIOD	LAGPERIOD	PERIODBEG	PERIODEND
Monthly	01-2018	12-2017	2018-01-01	2018-01-31

[emrancaan]

Thanks Chris, final dataset seems fine but I also need LagperiodBeg and LagperiodEnd. I used lag() but it didn't work.

[ChrisNZ]

You can't use lag() in sql. Just use the same logic as for the other fields .

[emrancaan]

I cannot generate he required output fully It is failing at

Quarterly

03-2017

2017-01-01

2017-03-31

05-2017

2017-05-01

2017-05-31

[Astounding]

To get "prior" period dates, use INTNX.  Just change the 0 to -1 to go back one period.