SAS PROC means (two variants together) PROC means data=d mean; 
var a;
class b; var a;
run; 

I want to perform the "PROC means" for continuous "var a":
1) in general and
2) by classes.
But it performed by the classes only.
How to make procedure for "var a" here in general too?

P.S. SAS WARNING: Analysis variable "a" was defined in a previous statement, duplicate definition will be ignored.
Just run 

PROC means data=d mean; var a; run;

for overall data