How the below query is working

Question

Hi,
I am newly joined in the group.
the emp table has 5 rows as below
100     ram     10000.00     10
200     kumar     15000.00     10
300     william     20000.00     10
400     ravi     25000.00     10
500     victor     30000.00     10
i execute the below query
select ename,sal from emp_test where case when sal < 10000 then sal + 1000
when sal < 20000 then sal + 2000
else sal
end < 20000
it gives the below output
ram     10000.00
kumar     15000.00
How the above query is working?
Please explain. thanks in advance

Answer 1

If you want it to show the changed salary, it has to be in the select line not the where:
select ename,
       (case when sal < 10000 then sal + 1000
           when sal < 20000 then sal + 2000
           else sal
        end) sal from emp_test
where  case when sal < 10000 then sal + 1000
           when sal < 20000 then sal + 2000
           else sal
        end < 20000