Changing character length of base

[Taker123]

So I'm getting an warning when appending.

Warning: Variable 'Class Name'n has different lengths on BASE and DATA files (BASE 32 DATA 38)

Warning: Variable 'Parent Name'n has different lengths on BASE and DATA files (BASE 32 DATA 38)

How would I get base and data to match by changing BASE? So Class Name has BASE 38 and Parent Name has BASE 38 so they all match. I can't seem to find any examples on how to do this correctly.

What I have done is this in an attempt to fix:

Data dmbi.test;
set dmbi.february;
length 'Class Name'n $38
'Parent Name'n $38;
run;

But I still get the error.

Thank you.

[Tom · Accepted solution]

You cannot change the length of a character variable once the data step compiler has already set it.

Move the LENGTH statement before the SET statement if you want to use it to change the length of variables that exist in the input dataset(s).