[jleedev]

Mysql also applies additional rounding to floats if you're not careful:

  mysql> create table t(f float);
  Query OK, 0 rows affected (0.02 sec)

  mysql> insert into t(f) values (999999),(1000000),(1000001);
  Query OK, 3 rows affected (0.00 sec)
  Records: 3  Duplicates: 0  Warnings: 0

  mysql> select distinct f from t;
  +---------+
  | f       |
  +---------+
  |  999999 |
  | 1000000 |
  | 1000000 |
  +---------+
  3 rows in set (0.00 sec)

  mysql>