Issue Creating a Table based on Macro's Parameter Name - sas

Question

So I will briefly explain my code structure before I dive into the issue.
I've a macro
%Sales (Outdata= , dt =, Outdata2= , Outdata3= );
(
I create a table &outdata by (Select * from XYZ);
Proc SQL;
Create table &Outdata._1 as
(
)
%mend Sales
Now I call the macro
%Sales (Outdata = sales_final_Oct17, dt='2017-10-01');
Libname ABCDEFG
I Create a data set
Data ABCDEFG.all_sales_test;
Set ABCDEFG. all_Sales
sales_final_Oct17_1;
incur_month = month(rept_dt);
run;
Above (1 to 3) is the original code flow and it works fine.
My Problem:
I'm using a dynamic way of generating file name for each month (so that each month I do not manually enter file_name_month and date.
File name code
%let Last_Month = intnx('month', current_date,-1, "beginning");
Name = 'Sales_final';
Last_Month_Name = name|| put(&last_month, monyy7.);
Call SYMPUTX('Last_Month_Name_v', Last_Month_Name);
run;
Call Macro
%Sales(outdata=&Last_Month_Name, dt = 'Dynamic date');
Till this point everything works fine. The moment I create a data set similar to step 3 (above), the code breaks.
Libname ABCDEFG
Data ABCDEFG.all_sales_test;
Set ABCDEFG.all_Sales
Last_Month_Name_1;
incur_month = month(rept_dt);
run;
> Error Message: File ABCDEFG.LAST_MONTH_NAME_1.DATA does not exist.
What should I do to get rid of this error? It seems, if I pass a static name in the macro and then use the same name with "_1" it works fine but when I pass dynamic reference, then the data Set step fails with the above error message.
Any help is much appreciated. I'm new to SAS so excuse me if it's a silly question. Thanks.

Answer 1

In (1) the macro code is using the value of the macro parameter (or local macro variable) OUTDATA to create a dataset. In (2) you are supplying a value for OUTDATA in your call and in (3) you are using the same value again in the set statement.
One way to not have to type the value twice is to store the value into a macro variable then just reference that macro variable's value in steps (2) and (3).
So in (4) you did create a macro variable,Last_Month_Name_v , but you then used the value of a different macro variable, &Last_Month_Name in the macro call. But instead of using the macro variable in the set statement you just referenced some other dataset,Last_Month_Name_1 , that you never mentioned before at all.
Here are the simplified key steps in the process you want for how to create and use the macro variable. I have put in ... to show where I have left out parts of a statement or statements so we can concentrate on the flow of the macro variable and its value.
First you set the macro variable to some name that you want to use. Let's just use anything as the name for this example.
%let last_month_name= anything;
Then you use the value in the macro call to create the dataset. Notice the & before the name, that is what tells the macro processor to replace the name with the value. The period after the name tells the macro processor that is the end of the macro variable name.
%sales(outdata=&last_month_name. .... )
Then you can use the value again later when you want to tell the set statement which dataset to read.
set .... &last_month_name. ;
Now your posted macro %sales does not actually create the dataset named anything. Instead it appears to create a dataset named anything_1. Personally I don't know why that is there, but if you keep it that way then you need add the _1 back to the end of the macro variable's value in the set statement. Just do it in the same way that you did in the macro's code.
set .... &last_month_name._1 ;

Answer 2

Working with macros is one of the harder parts of SAS and can be very confusing to newcomers. Below is a simplified working example that demonstrates the approach I would take.
First we dynamically calculate the name of the table we want to save the results to:
%let current_date = %sysfunc(date());
%let last_month = Sales_final_%sysfunc(intnx(month, &current_date, -1, beginning), monyy7.);
%put &=last_month;
The output from the put statement in the above step is:
LAST_MONTH=Sales_final_OCT2017
Note that in the above code, I'm passing two parameters to %sysfunc(). The first parameter is the call to the intnx() function. The second parameter (monyy7.) is what format to apply to the result being returned from the function call.
Also note that there is no need to concatenate the prefix (Sales_final_) to the %sysfunc() result because when working with the macro language, the result of %sysfunc() is subsituted in place. There is no concatenation operator in the macro language at all - everything is based off of macro substitution.
Then it's a simple case of passing that value into the macro as shown below:
%macro sales(outdata=);
proc sql;
create table &outdata._1 as select * from sashelp.class;
quit;
%mend;
%sales(outdata=&last_month);
You should be able to modify the above into what you need.