= SAS Macro Variables =

<<TableOfContents>>

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== Defining Variables ==

A macro variable can be defined like:

{{{
%let LABEL = VALUE;
}}}

A macro's value can be access like:

{{{
&LABEL
}}}



=== Using Macros ===

A macro definition can reference another macro. To use a SAS function in defining a macro variable, the `%sysfunc` macro function must be used. 

{{{
%let mon       = 1;
%let curr_yr   = %sysfunc(year("&sysdate"d));
%let mon_title = %sysfunc(mdy(&mon,1,&curr_yr), monname9.);
%let mon_title = %sysfunc(left(%qsysfunc(mdy(&mon,1,&curr_yr), monname9.)));
}}}

For considerations on using macro functions including `%sysfunc`, see [[SAS/MacroFunctions|Macro Functions]].

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== Defining Variables in the Data Step ==

A macro variable can be set by `symputx` calls, and retrieved by `symget` calls. This enables programmatic creation and use of macros, i.e. for aggregation of data.

{{{
data _NULL_;
  set LIBREF.TABLE end=lastobs;
  retain sum_sales 0;
  sum_sales = sum_sales + sales;
  if lastobs then call symputx('total_sales', put(sum_sales, dollar10.2));
run;

data temp;
  set LIBREF.TABLE;
  total_sales = input(symget('total_sales'), dollar10.2);
run;
}}}



=== Setting ===

`symput` and `symputx` both take two string arguments-the macro variable name and its value. In order to set a numeric value into the macro, it must be converted using `put`.

`symput` and `symputx` are very similar. The latter is silent and trims leading spaces, whereas the former will log information and preserve leading spaces. Generally, `symputx` is the right option.



=== Accessing ===

`symget` and `symgetn` take a single string argument-the macro variable name. The variable must be defined.

`symget` is for character data, while `symgetn` implicitly converts to numeric.

`resolve` works in a similar manner, but takes a macro label with the trigger prefix (`&` or `%`), and can be used to get the value of a macro variable or function. For more details, see [[#Macro-Functions-In-The-Data-Step|below]].

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== Defining Variables in the SQL Process ==

A macro variable can be set by `PROC SQL`. This has many of the same benefits as with the data step.

{{{
proc sql noprint;
  select sum(sales) format=dollar10.2
    into :total_sales
    from LIBREF.TABLE;
quit;
}}}

`proc sql` also sets three background macro variable.

 * `SQLOBS` is the number of rows produced with a SELECT statement
 * `SQLRC` is the return code from the ultimate statement
 * `SQLOOPS` is the number of iterations from the ultimate (i.e., highest-level) loop

See [[SAS/SQL|here]] for more details.

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== Scope ==

A macro variable defined by open code is stored in the global table. A macro variable defined in a separate program is local. By the nature of SAS, most custom macros will be global.

If necessary, it is possible to force local resolution of a label.

{{{
%local A;
%let A=B;
}}}



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