Making a Macro Case Insensitive - Why do I have to use a macro variable?

[SasStatistics]

I want to make a Macro case in-sensitive so that if the user for instance writes Type or TYpE in the positional argument (see code below) it does not matter. My code is: 

%macro Customers(Type); 
	%let Type = %sysfunc(upcase(&Type)); *why is Type = upcase(Type) wrong? I.e. why do I have to create a macro variable?;

	title "&type Customers"; 
	proc sql number;
	select Name, Age_Group, Type
	    from mc1.customers 
	    where upcase(Type) contains "&Type"; 
	quit; 
	title;
%mend Customers; 

Why would Type = upcase(Type) be wrong? 

So the question is, why do I have to create a macro variable for the positional argument in this case?

Thanks. 

[FreelanceReinh · Accepted solution]

Hello @SasStatistics,

Macro parameters are local macro variables. You cannot use the DATA step syntax varname=value of an assignment statement for macro variables. The %LET statement in your macro does not create a new macro variable, it changes the value of the existing macro variable Type.

But you can simplify the correct %LET statement by using the %UPCASE macro function:

%let Type = %upcase(&Type);

I would be a bit concerned about your WHERE condition using the CONTAINS operator because, for example, it would also select INACTIVE customers when you actually want ACTIVE customers.

[ChrisNZ]

> Why would %let type = upcase(Type) be wrong? 

It's not wrong.  The macro variable TYPE simply contains letters and parentheses.