SAS retain value and assign to new variable - sas

Question

I have the following data
EMPID XVAR SRC
ABC PER1 1
ABC 2
XYZ PER1 1
XYZ 2
LMN PER1 1
LMN 2
LMN PER2 1
LMN 2
LMN 2
LMN PER3 1
LMN 2
I need to create a new variable _XVAR for records where SRC=2 based on the value for XVAR on the previous record (where SRC=1)
The output should be like:
EMPID XVAR SRC _XVAR
ABC PER1 1
ABC 2 PER1
XYZ PER1 1
XYZ 2 PER1
LMN PER1 1
LMN 2 PER1
LMN PER2 1
LMN 2 PER2
LMN 2 PER2
LMN PER3 1
LMN 2 PER3
I am trying the following, but it isnt working;
data t003;
set t003;
by EMPID;
retain XVAR;
if SRC eq 2 then _XVAR=XVAR;
run;

Answer 1

It can also be done by saving the XVAR in a new variable (last_XVAR), retaining it and dropping it (you dont want it in the output). Then use that one to assign _XVAR. Note that you need to set last_XVAR after the IF, or the current XVAR is used in the assignment of _XVAR.
Your code, edited:
data t003;
set t003;
by EMPID;
length _XVAR last_XVAR $ 10;
if SRC eq 2 then _XVAR = last_XVAR;
last_XVAR = XVAR;
retain last_XVAR;
drop last_XVAR;
run;

Answer 2

You can use LAG to retrieve prior row values and conditionally use that value in an assignment.
Sample data
data have; input
EMPID $ XVAR $ SRC; datalines;
ABC PER1 1
ABC . 2
XYZ PER1 1
XYZ . 2
LMN PER1 1
LMN . 2
LMN PER2 1
LMN . 2
LMN . 2
LMN PER3 1
LMN . 2
run;
Example code
data want;
set have;
lag_xvar = lag(xvar);
if src eq 2 then do;
if lag_xvar ne '' then _xvar = lag_xvar;
end;
else
_xvar = ' ';
retain _xvar;
drop lag_xvar;
run;