Padding text with leading zeros in Teradata

In order to pad a number with leading zero Teradata you can do as follows:

create set table my_table ,no fallback ,
no before journal,
no after journal,
checksum = default
( a integer )
primary index ( a );

insert into my_table select 25;
insert into my_table select 12345;
insert into my_table select 0;

select substr(
'00000' || cast( a as varchar(5) ),
characters( cast( a as varchar(5) ) ),
5 )
from my_table;

The relevant part lies in the use of the functions substr and characters.