The following bug has been logged online:
Bug reference: 3435
Logged by: Carlos Quintero
Email address: carlos.quintero.sspa@juntadeandalucia.es
PostgreSQL version: 8.2.4
Operating system: Linux RedHat Enterprise 3
Description: problem with substring function
Details:
Hi,
I like to use a numerical expression as parameter for the substring
function, but it works always as i use regular expressions. Please, try
this:
select substring('1234' from to_number('3', '999999') for 3);
What returns a empty string:
substring
-----------
(1 fila)
But the right result must be this:
select substring('1234' from 3 for 3);
substring
-----------
34
(1 fila)
If i use other numbers, i got even some errors:
select substring('1234' from to_number('33', '999999') for 3);
ERROR: la expresión regular no es válida: invalid backreference number
CONTEXTO: función SQL «substring» en la sentencia 1
This is a sample, really i like to use an expression using date_part() as
the first parameter for substring.
Best Regards,
Carlos