MySQL中删除带有索引的字段后，索引会自动删除么？

Question

MySQL表中加一个字段并添加了Index索引，现在把字段删除后对该字段的索引是否还存在？若存在，后期要怎么删除该索引？

附上执行的sql语句:

ALTER TABLE `mytab` ADD COLUMN `is_export`  enum('yes','no') CHARACTER SET utf8 COLLATE utf8_general_ci NOT NULL DEFAULT 'no' COMMENT '是否已经导出' AFTER `start_time`;

CREATE INDEX `is_export` ON `mytab`(`is_export`) USING BTREE ;

Answer 1

http://dev.mysql.com/doc/refman/5.6/en/alter-table.html

If columns are dropped from a table, the columns are also removed from
any index of which they are a part. If all columns that make up an
index are dropped, the index is dropped as well.

所以对你的问题, 字段删除后对该字段的索引 不存在了