Why is Oracle's to_char() function adding spaces?

Question

Why is Oracle\'s to_char() function adding spaces?

select length(\'012\'), 
       length(to_char(\'012\')), 
       length(to_char(\'12\', \'000\')         


        

Answer 1

Be aware when using the 'fm' syntax it will not include any values after the decimal place unless specified using zeros. For example:

SELECT TO_CHAR(12345, 'fm99,999.00') FROM dual                               

returns: '12,345.00'

SELECT TO_CHAR(12345, 'fm99,999.99') FROM dual                            

returns: '12,345.'

As you can see this would be an issue if you are expecting two zeros after the decimals place (maybe in fee reports for example).