PostgreSQL开关查询到功能

Question

此查询有效，但我想将其更改为在区域是varchar，女人和男人整数时如何做到这一点？

Select region,man, woman,
Case
When woman > man then woman - man
When woman < man then man - woman
ELSE 0
END
AS test
FRom people;

Answer 1

只要它一个：

create function ops()
  returns table (region varchar, man integer, woman integer, test integer)
as
$$
Select region,man, woman,
       Case 
         When woman > man then woman - man
         When woman < man then man - woman
        ELSE 0 
       END AS test
From people;
$$
language sql;