fbsql_affected_rows() returns the number of rows affected by the last INSERT, UPDATE or DELETE query associated with link_identifier.
If you are using transactions, you need to call fbsql_affected_rows() after your INSERT, UPDATE, or DELETE query, not after the commit.
If the last query was a DELETE query with no WHERE clause, all of the records will have been deleted from the table but this function will return zero.
When using UPDATE, FrontBase will not update columns where the new value is the same as the old value. This creates the possibility that fbsql_affected_rows() may not actually equal the number of rows matched, only the number of rows that were literally affected by the query.