create table test_case_when (
a varchar2(5),
b varchar2(5)
);
insert into test_case_when values ('*','*');
insert into test_case_when values ('+','+');
insert into test_case_when values ('-','-');
insert into test_case_when values ('.','.');
select a,
case
when b = '*' then 'star'
when b = '+' then 'plus'
when b = '-' then 'minus'
else '????'
end
from test_case_when;