Add flags after comparing columns of dates - sas

Question

suppose to have the following data set.
ID Hired Start_date End_date Flag_Start Flag_End
0001 1-1900 01JAN2018 21DEC2018 1 2
0001 1-1900 01JAN2019 01DEC2020 2 2
0002 10-2020 26MAR2020 03MAY2020 1 2
0003 03-2021 18DEC2020 31DEC2020 1 2
..... ....... ......... ......... ........... ...........
I would like the desired output. Sorry if I ask you but I'm a newbie and this seems to be a very difficult task with SAS. I'm familiar with R.
Desired output:
ID Hired Start_date End_date Flag_Start Flag_End
0001 1-1900 01JAN2018 21DEC2018 1 2
0001 1-1900 01JAN2019 01DEC2020 2 3
0002 03-2020 26MAR2020 03MAY2020 1 0
0003 03-2021 18DEC2020 31DEC2020 1 3
..... ....... ......... ......... ........... ...........
So, for each ID, if, after sorting, the last End_date is "x" and the "Hired" is 1-1900 then in Flag_End add 3 otherwise if Hired is < End_date add 0 otherwise if Hired is > End_date but not 1-1900 add 3.
Thank you in advance

Answer 1

I think this is what you want.
The Hired Date does not match between your two posted data sets. I chose the second one (03-2020).
data have;
input ID $ Hired :anydtdte. (Start_date End_date)(:date9.) Flag_Start Flag_End;
format Hired Start_date End_date date9.;
datalines;
0001 1-1900 01JAN2018 21DEC2018 1 2
0001 1-1900 01JAN2019 01DEC2020 2 2
0002 03-2020 26MAR2020 03MAY2020 1 2
0003 03-2021 18DEC2020 31DEC2020 1 2
;
data want;
set have;
by ID;
if last.ID then do;
if Hired = '01jan1900'd then flag_end = 3;
else if Hired < End_date then flag_end = 0;
else if Hired >= End_date then flag_end = 3;
end;
run;