I moved from postgres 7.0.2 to 8.0.1,
in the 7.0.2 version I process the next query, and it succeed:
select ichar(letra_ascii) || '-' || substr('00000' ||num_factura,length
(num_factura)+1,5) as factura from facturas
but in 8.0.1 it outputs the next error:
ERROR: not exist the function ichar(integer)
HINT: any function match with the arguments types.
Add explicit cast of types