Using DATA step to manipulate date values

[TurnTheBacon]

I need to do a quick ad-hoc operation in user written code. The program needs to locate row 2, store its variable "from_dttm" minus 1 second into the new variable "newdate", then locate row 4 and put "newdate" into "to_dttm".

I know I'm not handling the date values correctly in the code below, and would appreciate any advice on how to resolve this. Thank you.

data &_output;

  set work.replace;

  format newdate NLDATM21.;

   if _n_ = 2 then do;

       newdate = from_dttm-1;

  end;

   if _n_ = 4 then do;

        to_dttm = newdate;

  end;

run;

[ballardw · Accepted solution]

to keep the values of newdate across "rows" you need to add a retain statement.

retain newdate . ;

If you need to do this to many records you'll probably need a different approach.