可以用這個命令：

show index from table_name;

得到輸出：

+------------------+------------+------------+--------------+-------------+-----------+-------------+----------+--------+------+------------+---------+---------------+
| Table            | Non_unique | Key_name   | Seq_in_index | Column_name | Collation | Cardinality | Sub_part | Packed | Null | Index_type | Comment | Index_comment |
+------------------+------------+------------+--------------+-------------+-----------+-------------+----------+--------+------+------------+---------+---------------+
| table_name |          0 | PRIMARY    |            1 | id          | A         |      661757 |     NULL | NULL   |      | BTREE      |         |               |
| table_name |          0 | product_id |            1 | product_id  | A         |      661757 |     NULL | NULL   |      | BTREE      |         |               |
+------------------+------------+------------+--------------+-------------+-----------+-------------+----------+--------+------+------------+---------+---------------+
2 rows in set (0.00 sec)

mysql查一張表有哪些索引