How to find less than by decode? - sql

Question

ORA-00907: missing right parenthesis
00907\. 00000 - "missing right parenthesis"
SELECT last_name
,salary
,DECODE(salary, salary < 6000, 0.36,
salary < 8000, 0.38,
salary < 10000, 0.4,
salary < 12000, 0.42,
salary < 14000, 0.44,
salary < 16000, 0.45) as "TAX RATE"
FROM employees;

Answer 1

Don't make your life a misery. Use CASE expression instead of DECODE.
select case when salary < 6000 then 0.36
when salary < 8000 then 0.38
...
when salary < 16000 then 0.45
else null
end as tax_rate
from employees
If you'd want to do it with DECODE, you'd use SIGN function (to check whether salary is less than certain amount), and then nest as many DECODEs as necessary. That works, but is a nightmare to maintain.
I don't have your table so I'll try to illustrate it using Scott's emp:
SQL> select ename, sal,
2 decode(sign(sal - 1000), -1, 'less than 1000',
3 decode(sign(sal - 1500), -1, 'less than 1500',
4 decode(sign(sal - 2000), -1, 'less than 2000'))
5 ) rate
6 from emp;
ENAME SAL RATE
---------- ---------- --------------
SMITH 840 less than 1000
ALLEN 1600 less than 2000
WARD 1250 less than 1500
JONES 2975
MARTIN 1250 less than 1500
BLAKE 2850
CLARK 2450
SCOTT 3000
KING 5000
<snip>
If you compare it to CASE, difference is more than obvious:
SQL> select ename, sal,
2 case when sal < 1000 then 'less than 1000'
3 when sal < 1500 then 'less than 1500'
4 when sal < 2000 then 'less than 2000'
5 end rate
6 from emp;
ENAME SAL RATE
---------- ---------- --------------
SMITH 840 less than 1000
ALLEN 1600 less than 2000
WARD 1250 less than 1500
JONES 2975
MARTIN 1250 less than 1500
<snip>