mysql删除索引

Question

表的结构如下：
| act | CREATE TABLE act (
id bigint(20) NOT NULL AUTO_INCREMENT,
mac varchar(12) NOT NULL,
time datetime DEFAULT NULL,
pid varchar(100) NOT NULL,
buffertime varchar(100) NOT NULL,
PRIMARY KEY (id),
KEY mac_index (mac),
KEY time_index (time),
KEY pid_index (pid),
KEY buffertime_index (buffertime)
) ENGINE=MyISAM DEFAULT CHARSET=latin1 |

删除表的索引，出现了如下问题

MariaDB [TecentAct]> drop index index_pid on act;
ERROR 1091 (42000): Can't DROP 'index_pid'; check that column/key exists
是sql语句的问题么？

Answer 1

你是不是在pid上做了外键索引？