Question

what is advantages of using SQLite3::createFunction() over simple php function?

Answer 1

You can use it in SQL-queries

SELECT col1, my_function(col2) FROM tab;

With PHP-functions you must iterate over the result set on your own. I don’t know, how exactly it is implemented, but as far as I know SQLite3 works with cursors and therefore the function should only get executed, when you retrieved a row.