I'm dealing with lots of different currencies in my application, and I want to know what the "best" way is to store them in an SQLite3 database.
I'm leaning towards a fixed-point representation (i.e. store them as integers, where $3.59 gets stored as 359, ¥400 stored as 40000). Is this a good idea? What if my input data later changes and requires more precision?
Given that SQLite 3 will use up to 8 bytes to store INTEGER types, unless you are going to have numbers greater than 10^16, you should be just fine.
To put this in perspective, the world gross domestic product expressed in thousandths of a USD (a mill) is about 61'000'000'000'000'000 which sqlite3 has no problem expressing.
sqlite> create table gdp (planet string, mills integer);
sqlite> insert into gdp (planet, mills) values ('earth', 61000000000000000000);
sqlite> select * from gdp;
earth|61000000000000000000
Unless you are handling interplanetary accounting, I don't think you have to worry.