问题
I need to replace comma with point and then i need my value to be a number. So i wrote this:
select replace('12345,6789', ',' , '.') from dual --it works fine
but then I want to convert to_number that value and I get the error:
"invalid number"
回答1:
The to_number() function uses the session's NLS_NUMERIC_CHARACTERS setting to decide how to interpret commas and periods. If you know your string will always have a comma as decimal separator you can override that as part of the call, using the optional third argument; although that does mean you have to specify the format model:
select to_number('12345,6789', '9999999999D9999', 'NLS_NUMERIC_CHARACTERS='',.''')
from dual;
TO_NUMBER('12345,6789','9999999999D9999
---------------------------------------
12345.6789
You don't need a separate replace() step.
You can also change the session's setting with ALTER SESSION SET NLS_NUMERIC_CHARACTERS=',.';, but you may not be able to control the setting in every client that has to run your code.
回答2:
The decimal separator is defined in your locale. Here it looks like it is ,. So you need not to do the replacement before converting your string:
select to_number('12345.6789') from dual --should work already
Or change your locale:
alter session set NLS_NUMERIC_CHARACTERS= '.,';
select to_number('123'||'.'||'456') from dual;
select to_number(replace('12345,6789', ',' , '.')) from dual
来源：https://stackoverflow.com/questions/38739525/decimal-separator-oracle