Populate fields in SAS by ID and Date

Question

My dataset looks like this:

AsAtDate  ReleaseDate ID Var1 Var2 ... Var5
200701     200601      1   x    .    
200702     200601      1   .    a
200703     200601      1   .    .
200701     200702      2   .    b 
200702     200702      2   y    b
200703     200702      2   y    .
200702     200501      3   z    .
200703     200501      3   .    .

I want my results to look like this:

AsAtDate  ReleaseDate ID Var1 Var2 ... Var5
200701     200601      1   x    a    
200702     200601      1   x    a
200703     200601      1   x    a
200701     200702      2   .    . 
200702     200702      2   y    b
200703     200702      2   y    b
200702     200501      3   z    .
200703     200501      3   z    .

How do I get my data to consider the ReleaseDate as in, if ReleaseDate is earlier than AsAtDate then populate the fields by ID.

Answer 1

Building on your solution, we can add a CASE statement to conditionally fill in the data as needed.

proc sql;
create table want as
select *, 
       case when ReleaseDate>AsAtDate then " " 
       else max(Var1) 
       end as _Var1
from have
group by ID
order by ID, AsAtdate;
quit;