%let is not working in data step block

[thanikondharish]

data _null_ ;
call symput('name','aaa') ;
%let name=bbb ;
run;
%put &name ;

If I execute above program is showing (aaa) value . why %let is not working and what is the logic behind that.

Kindly explain?

[Shmuel]

%let is a declarative statement and is been executed outside the data step.

Your code is equal to:

%let name=bbb ;
data _null_ ;
call symput('name','aaa') ;
run;
%put &name ;

[Kurt_Bremser]

The macro processor is a PREprocessor, doing its work when the code is read and prepared for compilation/execution.

To overwrite the value set by the data step, you have to move the %LET after the step boundary (after the RUN statement).