MySQL 错误:缺少约束索引 [英] MySQL error: Missing index for constraint

问题描述

我正在我的数据库中创建 2 个表:

DROP TABLE IF EXISTS `med_pharmacy`;如果不存在则创建表`med_pharmacy`(`med_pharmacy_id` int(11) NOT NULL AUTO_INCREMENT,`med_id` int(11) 非空，`med_barcode` varchar(45) 默认为空，`med_received` 日期默认为空，`med_expiry` 日期默认为空，`med_tablet` int(11) 默认为空，`med_pill` int(11) 默认为空，`clinic_id` varchar(45) 默认为空，主键(`med_pharmacy_id`)，密钥`fk_med_pharmacy_medication1_idx`(`med_id`)) ENGINE=InnoDB AUTO_INCREMENT=1261 DEFAULT CHARSET=utf8mb4;

与:

DROP TABLE IF EXISTS `medication`;创建表`药物`(`med_id` int(11) 非空，`med_name` varchar(75) 非空，`med_date_ added` 日期默认为空，`clinic_id` varchar(45) 默认为空，`med_type` varchar(15) 默认 NULL) 引擎=InnoDB 默认字符集=utf8mb4;

当我在 wamp 中运行查询时，出现此错误:

SQL 查询:

ALTER TABLE `med_pharmacy`添加约束`fk_med_pharmacy_medication1`外键(`med_id`)参考`medication` (`med_id`) ON DELETE CASCADE ON UPDATE CASCADE MySQL

<块引用>

说:文档

#1822 - 添加外键约束失败.引用表中缺少约束fk_med_pharmacy_medication1"的索引'药物'

表格已经存在，但我更改了一个字段.

解决方案

外键中引用的列必须编入索引.您需要在 medication.med_id 上添加索引.事实上，这应该是表的主键.

ALTER TABLE drug ADD PRIMARY KEY (med_id);

I am creating 2 tables in my database:

DROP TABLE IF EXISTS `med_pharmacy`;
CREATE TABLE IF NOT EXISTS `med_pharmacy` (
  `med_pharmacy_id` int(11) NOT NULL AUTO_INCREMENT,
  `med_id` int(11) NOT NULL,
  `med_barcode` varchar(45) DEFAULT NULL,
  `med_received` date DEFAULT NULL,
  `med_expiry` date DEFAULT NULL,
  `med_tablet` int(11) DEFAULT NULL,
  `med_pill` int(11) DEFAULT NULL,
  `clinic_id` varchar(45) DEFAULT NULL,
  PRIMARY KEY (`med_pharmacy_id`),
  KEY `fk_med_pharmacy_medication1_idx` (`med_id`)
) ENGINE=InnoDB AUTO_INCREMENT=1261 DEFAULT CHARSET=utf8mb4;

AND:

DROP TABLE IF EXISTS `medication`;

CREATE TABLE `medication` (
  `med_id` int(11) NOT NULL,
  `med_name` varchar(75) NOT NULL,
  `med_date_added` date DEFAULT NULL,
  `clinic_id` varchar(45) DEFAULT NULL,
  `med_type` varchar(15) DEFAULT NULL
) ENGINE=InnoDB DEFAULT CHARSET=utf8mb4;

And when I run the queries in wamp I got this error:

SQL query:

ALTER TABLE `med_pharmacy`   
ADD CONSTRAINT `fk_med_pharmacy_medication1` 
FOREIGN KEY (`med_id`) 
REFERENCES
`medication` (`med_id`) ON DELETE CASCADE ON UPDATE CASCADE MySQL

said: Documentation

#1822 - Failed to add the foreign key constaint. Missing index for constraint 'fk_med_pharmacy_medication1' in the referenced table 'medication'

The tables already exists but I changed one field.

解决方案

The column referenced in a foreign key must be indexed. You need to add an index on medication.med_id. In fact, this should probably be the primary key of the table.

ALTER TABLE medication ADD PRIMARY KEY (med_id);

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