不能删除MariaDb表上的索引？

Question

我很难删除表userprofile_userprofile的索引：

以下是索引：

MariaDB [djdb]> SHOW INDEX FROM userprofile_userprofile;
+-------------------------+------------+---------------+--------------+-------------+-----------+-------------+----------+--------+------+------------+---------+---------------+
| Table                   | Non_unique | Key_name      | Seq_in_index | Column_name | Collation | Cardinality | Sub_part | Packed | Null | Index_type | Comment | Index_comment |
+-------------------------+------------+---------------+--------------+-------------+-----------+-------------+----------+--------+------+------------+---------+---------------+
| userprofile_userprofile |          0 | PRIMARY       |            1 | id          | A         |       14566 |     NULL | NULL   |      | BTREE      |         |               |
| userprofile_userprofile |          1 | id-userid-idx |            1 | id          | A         |       14566 |     NULL | NULL   |      | BTREE      |         |               |
| userprofile_userprofile |          1 | id-userid-idx |            2 | user_id     | A         |       14566 |     NULL | NULL   |      | BTREE      |         |               |
+-------------------------+------------+---------------+--------------+-------------+-----------+-------------+----------+--------+------+------------+---------+---------------+

当我尝试：

MariaDB [djdb]> ALTER TABLE  userprofile_userprofile DROP INDEX id-userid-idx;

我收到此错误：

ERROR 1064 (42000): You have an error in your SQL syntax; check the manual that corresponds to your MariaDB server version for the right syntax to use near '-userid-idx' at line 1

我也试过

DROP INDEX  id-userid-idx ON  userprofile_userprofile;

但是得到同样的错误。 我想知道这里有什么问题，我怎么能放弃索引？