SQLite function to format numbers with leading zeroes?

Question

I’ve got an SQLite database that will need to contain products. Those products have a fixed-format composite product number, consisting of category, group and product numbe

Answer 1

I know this is an old question, but the following is simpler:

--  zero-pad to 4 digits:
select substr('0000'||3,-4);

substr does not require a length if you’re selecting to the end.