SQL CASE expression:
Select :

I) Condition : A

select ename, sal, job,
case
when ename= 'SMITH' then '25%'
when job ='CLERK' then '15%'
when JOB='SALESMAN' then '20%'
else ' 0%'end as raise
from emp order by raise

II) Condition B

select ename, sal, job,
case when job ='CLERK' then '15%'
when JOB='SALESMAN' then '20%'
when ename= 'SMITH' then '25%'
else ' 0%'
end as raise
from emp order by raise
 
Please Note the conflict between two tuples, namely "SMITH/COMM" AND "CLERK/COMM", where the target output filed ("RAISE") was tried to be altered with two clauses.

A) OUTPUT :  ename= 'SMITH' then '25%' 

 

B) OUTPUT :  job ='CLERK' then '15%'

Oracle
PostgreSQL