I am having difficulty using an IF statement within a SAS Macro - sas

Question

I am setting up a batch script in SAS, I want it to run monthly and output to table, the code works when running manually but I am having difficulty setting up the macros.
I have created 3 macros, one for the previous month (please ignore the hard coded 12 and the commented out code, I was just testing if it worked or not, the commented out code will remain and the hard coded 12 will be removed when I can get it working), one for the current year and one for the previous year. The issue I will have is that the script grabs month end data, so come January the year will be set to 2020 but the month will be looking for December data.
`%let pmonth = 12 /*%sysfunc(month(%sysfunc(intnx(month,"&sysdate"d ,-1))))*/;`
`%put &pmonth;`
`%let year1 = %sysfunc(year("&sysdate"d));`
`%put &year1;`
`%let year2 = %sysfunc(year(%sysfunc(intnx(year,"&sysdate"d ,-1))));`
`%put &year2;`
`%macro year;
%if &pmonth = 12 %then %do;
&year2;
%end;
%else %do;
&year1;
%end;
%mend;
%year;`
What I would like is for the macro year, which is used in my code, to select correctly between year1 and year2 based on the month macro pmonth. I have played around a bit with the macros but if I'm honest, its not an area of SAS I've used that often.

Answer 1

A little terminology first. Your code has one macro defined, %YEAR. It does have three macro variables named YEAR1, YEAR2 and PMONTH. And there is no macro variable named YEAR that your code is either attempting to create or use. And your code does not have any IF statements. But there is one %IF statement inside the definition of the YEAR macro.
You probably will want to convert your macro variable values into actual DATE values to deal with the year issue. So if your input is two macro variables with YEAR and MONTH you can convert that into a date.
%let year1=2018;
%let month=1;
%let date=%sysfunc(mdy(&month,1,&year1));
Then if you want to find the end of the previous month you can use the date in the INTNX() function call.
%let end_of_prev_month=%sysfunc(intnx(month,&date,-1,e));
Then if you need to you can get the YEAR and MONTH for that new date.
%let year2=%sysfunc(year(&end_of_prev_month));
%let month2=%sysfunc(month(&end_of_prev_month));