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How to pull records with the last n number of dates

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Occasional Contributor
Posts: 12
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How to pull records with the last n number of dates

Good day.

 

I'm struggling with the problem of creating a report with the last 3 dates that is in my data set. So I should not hard code the dates that I want in the report, the dates should be determined by the data set itself. I've tried using proc sql to get the distinct dates that is present in my data set so I can use the latest 3 dates present, but I can't seem to figure out how to extract only the records with those dates from my data set. the code I used to get the distinct dates is:

proc sql ;
create table DISTINCTQ as
    select distinct QUARTER
        from SASUSER.QUARTER
            order by QUARTER DESC;

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‎02-20-2018 04:24 AM
Super User
Posts: 6,543

Re: How to pull records with the last n number of dates

I think this is headed in the right direction.  Here are a couple of changes I would recommend:

 

proc sort data=have out=temp;

by descending quarter;

run;

data want;

set temp;

by descending quarter;

n_dates + first.quarter;

if n_dates > 3 then stop;

drop n_dates;

run;

 

It's not clear how large your data set, and how important efficiency considerations would be.

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Super User
Super User
Posts: 9,227

Re: How to pull records with the last n number of dates

Posted in reply to HelpPlease

The problem is your using SQL, which is not built with postional rows in mind, only logical clauses.  Switch to using SAS (it is the language you are programming in for instance) and it is a simple problem:

proc sort data=sasuser.quarter out=distinctq;
  by quarter descending desc;
run;
data want;
  set distinctq;
  by quarter;
  c=ifn(first.quater,1,c+1);
  if c <= 3 then output;
run;
Solution
‎02-20-2018 04:24 AM
Super User
Posts: 6,543

Re: How to pull records with the last n number of dates

I think this is headed in the right direction.  Here are a couple of changes I would recommend:

 

proc sort data=have out=temp;

by descending quarter;

run;

data want;

set temp;

by descending quarter;

n_dates + first.quarter;

if n_dates > 3 then stop;

drop n_dates;

run;

 

It's not clear how large your data set, and how important efficiency considerations would be.

Occasional Contributor
Posts: 12

Re: How to pull records with the last n number of dates

Posted in reply to Astounding
thanks a lot! it worked perfectly.
☑ This topic is solved.

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