mysql - 当我尝试在 mysql 浏览器中使用此查询时，drop index indexname 无法正常工作

Question

当我尝试drop时出现错误我的索引，或者当我尝试使用此类查询 SHOW INDEX 查看我的索引时或DROP INDEX <INDEXNAME> 。

错误信息是:

mysqlserver version for right syntax to use near at line 1"".

Answer 1

查看索引

show index from myTable;
+---------+------------+----------+--------------+-------------+-----------+-------------+----------+--------+------+------------+---------+---------------+
| Table   | Non_unique | Key_name | Seq_in_index | Column_name | Collation | Cardinality | Sub_part | Packed | Null | Index_type | Comment | Index_comment |
+---------+------------+----------+--------------+-------------+-----------+-------------+----------+--------+------+------------+---------+---------------+
| myTable |          0 | PRIMARY  |            1 | id          | A         |           2 |     NULL | NULL   |      | BTREE      |         |               |
| myTable |          1 | title    |            1 | title       | A         |           2 |     NULL | NULL   | YES  | BTREE      |         |               |
| myTable |          1 | price    |            1 | price       | A         |           2 |     NULL | NULL   | YES  | BTREE      |         |               |
+---------+------------+----------+--------------+-------------+-----------+-------------+----------+--------+------+------------+---------+---------------+
3 rows in set (0.00 sec)

对于下降索引

ALTER TABLE TABLE_NAME DROP INDEX INDEX_NAME;

示例

show create table myTable\G
*************************** 1. row ***************************
       Table: myTable
Create Table: CREATE TABLE `myTable` (
  `id` int(11) NOT NULL AUTO_INCREMENT,
  `title` varchar(255) COLLATE utf8_unicode_ci DEFAULT NULL,
  `price` mediumint(9) DEFAULT NULL,
  PRIMARY KEY (`id`),
  KEY `title` (`title`),
  KEY `price` (`price`),
  KEY `idx_price_title` (`price`,`title`)
) ENGINE=InnoDB AUTO_INCREMENT=11 DEFAULT CHARSET=utf8 COLLATE=utf8_unicode_ci
1 row in set (0.02 sec)

我需要删除索引idx_price_title

ALTER TABLE myTable DROP INDEX idx_price_title;
Query OK, 0 rows affected (0.18 sec)
Records: 0  Duplicates: 0  Warnings: 0

检查索引是否存在

show create table myTable\G
*************************** 1. row ***************************
       Table: myTable
Create Table: CREATE TABLE `myTable` (
  `id` int(11) NOT NULL AUTO_INCREMENT,
  `title` varchar(255) COLLATE utf8_unicode_ci DEFAULT NULL,
  `price` mediumint(9) DEFAULT NULL,
  PRIMARY KEY (`id`),
  KEY `title` (`title`),
  KEY `price` (`price`)
) ENGINE=InnoDB AUTO_INCREMENT=11 DEFAULT CHARSET=utf8 COLLATE=utf8_unicode_ci
1 row in set (0.00 sec)