I want to format amounts to salary format, e.g. 10000 becomes 10,000, so I use to_char(amount, '99,999,99')
SELECT SUM(DECODE(e.element_name,'Basic Salary',to_char(v.screen_entry_value,'99,999,99'),0)) Salary,
SUM(DECODE(e.element_name,'Transportation Allowance',to_char(v.screen_entry_value,'99,999,99'),0)) Transportation,
SUM(DECODE(e.element_name,'GOSI Processing',to_char(v.screen_entry_value,'99,999,99'),0)) GOSI,
SUM(DECODE(e.element_name,'Housing Allowance',to_char(v.screen_entry_value,'99,999,99'),0)) Housing
FROM values v,
values_types vt,
elements e
WHERE vt.value_type = 'Amount'
this gives error invalid number because not all values are numbers until value_type is equal to Amount but I guess decode check all values anyway although what I know is that the execution begins with from then where then select, what's going wrong here?
You said you added decode(...), but it looks like you might have actually added sum(decode(...)).
You are converting your values to strings with to_char(v.screen_entry_value,'99,999,99'), so your decode() generates a string - the default 0 will be converted to '0' - giving you a value like '1,234,56'. Then you are aggregating those, so sum() has to implicitly convert those strings to numbers - and it is throwing the error when it tries to do that:
select to_number('1,234,56') from dual
will also get "ORA-01722: invalid number", unless you supply a similar format mask so it knows how to interpret it. You could do that, e.g.:
SUM(to_number(DECODE(e.element_name,'Basic Salary',to_char(v.screen_entry_value,'99,999,99'),0),'99,999,99'))
... but it's maybe more obvious that something is strange, and even if you did, you would end up with a number, not a formatted string.
So instead of doing:
SUM(DECODE(e.element_name,'Basic Salary',to_char(v.screen_entry_value,'99,999,99'),0))
you should format the result after aggregating:
to_char(SUM(DECODE(e.element_name,'Basic Salary',v.screen_entry_value,0)),'99,999,99')
fiddle with dummy tables, data and joins.