sql case in column and where section without repeating the case

Question

I have a sql statement like this but with a very long case expression in it and I need it in the where as well as in the column. Is there a way to use the case without repeating it in the column and where section.

select * from c.name, (case when c.age = 1 then 0 when c.age = 2 then 1 ... etc else -1 end;)
from customer c 
where (case when c.age = 1 then 0 when c.age = 2 then 1 ... etc else -1 end;) > 0

Answer 1

A simple way of consolidating would be to use a lateral join

select * 
from customer c,
lateral (values(case when c.age = 1 then 0 when c.age = 2 then 1 ... etc else -1 end))v(AgeCheck)
where AgeCheck > 0;