mysql> explain select language_id from sakila.film group by language_id;
+----+-------------+-------+-------+---------------+--------------------+---------+------+------+--------------------------+
| id | select_type | table | type | possible_keys | key | key_len | ref | rows | Extra |
+----+-------------+-------+-------+---------------+--------------------+---------+------+------+--------------------------+
| 1 | SIMPLE | film | range | NULL | idx_fk_language_id | 1 | NULL | 2 | Using index for group-by |
+----+-------------+-------+-------+---------------+--------------------+---------+------+------+--------------------------+
1 row in set (0.00 sec)
mysql> notee
|