错误 1005 (HY000)：无法创建 table 'shrewd_db.alert_disable_register'（错误编号：150）
ERROR 1005 (HY000): Can't create table 'shrewd_db.alert_disable_register' (errno: 150)
我想通过 运行 在 MySQL 中创建一个 table 跟随 SQL、
CREATE TABLE IF NOT EXISTS `shrewd_db`.`alert_disable_register` (
`id_alert_disable_register` MEDIUMINT NOT NULL AUTO_INCREMENT,
`id_label` MEDIUMINT UNSIGNED NULL,
`id_indicator` MEDIUMINT UNSIGNED NULL,
`id_user` MEDIUMINT UNSIGNED NULL,
`active` TINYINT(1) NULL DEFAULT 1,
`id_alert_disable_rule` MEDIUMINT NULL,
`id_escalation_plan` INT NULL,
PRIMARY KEY (`id_alert_disable_register`),
INDEX `id_escalation_plan_alert_rule_idx` (`id_alert_disable_rule` ASC),
INDEX `id_label_idx` (`id_label` ASC),
INDEX `id_indicator_idx` (`id_indicator` ASC),
INDEX `id_user_idx` (`id_user` ASC),
INDEX `id_escalation_plan_idx` (`id_escalation_plan` ASC),
CONSTRAINT `id_label`
FOREIGN KEY (`id_label`)
REFERENCES `shrewd_db`.`escalation_plan` (`id_label`)
ON DELETE NO ACTION
ON UPDATE NO ACTION,
CONSTRAINT `id_indicator`
FOREIGN KEY (`id_indicator`)
REFERENCES `shrewd_db`.`escalation_plan` (`id_indicator`)
ON DELETE NO ACTION
ON UPDATE NO ACTION,
CONSTRAINT `id_user`
FOREIGN KEY (`id_user`)
REFERENCES `shrewd_db`.`escalation_plan_task_group_has_user` (`id_user`)
ON DELETE NO ACTION
ON UPDATE NO ACTION,
CONSTRAINT `id_alert_disable_rule`
FOREIGN KEY (`id_alert_disable_rule`)
REFERENCES `shrewd_db`.`alert_disable_rule` (`id_alert_disable_rule`)
ON DELETE SET NULL
ON UPDATE SET NULL,
CONSTRAINT `id_escalation_plan`
FOREIGN KEY (`id_escalation_plan`)
REFERENCES `shrewd_db`.`escalation_plan` (`id_escalation_plan`)
ON DELETE NO ACTION
ON UPDATE NO ACTION)
ENGINE = InnoDB;
但我遇到以下错误，
ERROR 1005 (HY000): Can't create table
'shrewd_db.alert_disable_register' (errno: 150)
谁能帮我解决这个问题，:)
请在下面找到创建其他所需 table 的脚本，
CREATE TABLE `escalation_plan` (
`id_escalation_plan` int(10) unsigned NOT NULL AUTO_INCREMENT,
`id_indicator` mediumint(8) unsigned NOT NULL,
`id_label` mediumint(8) unsigned NOT NULL,
`pressure_waiting_hrs` int(11) NOT NULL DEFAULT '6',
PRIMARY KEY (`id_escalation_plan`),
KEY `fk_escalation_plan_escalation_plan1_idx` (`id_indicator`),
KEY `fk_escalation_plan_label1_idx` (`id_label`),
CONSTRAINT `fk_escalation_plan_escalation_plan1` FOREIGN KEY (`id_indicator`) REFERENCES `indicator` (`id_indicator`) ON DELETE NO ACTION ON UPDATE NO ACTION,
CONSTRAINT `fk_escalation_plan_label1` FOREIGN KEY (`id_label`) REFERENCES `label` (`id_label`) ON DELETE NO ACTION ON UPDATE NO ACTION
) ENGINE=InnoDB AUTO_INCREMENT=152 DEFAULT CHARSET=utf8;
CREATE TABLE `escalation_plan_task_group_has_user` (
`id_escalation_plan_task_has_user` int(10) unsigned NOT NULL AUTO_INCREMENT,
`id_user` mediumint(8) unsigned NOT NULL,
`id_escalation_plan_task_group` int(11) NOT NULL,
`text_alert` tinyint(1) NOT NULL DEFAULT '1',
`email_alert` tinyint(1) NOT NULL DEFAULT '1',
PRIMARY KEY (`id_escalation_plan_task_has_user`),
KEY `fk_escalation_plan_task_has_user_user1_idx` (`id_user`),
KEY `fk_escalation_plan_task_group_has_user_escalation_plan_task_idx` (`id_escalation_plan_task_group`),
CONSTRAINT `fk_escalation_plan_task_group_has_user_escalation_plan_task_g1` FOREIGN KEY (`id_escalation_plan_task_group`) REFERENCES `escalation_plan_task_group` (`id_escalation_plan_task_group`) ON DELETE NO ACTION ON UPDATE NO ACTION,
CONSTRAINT `fk_escalation_plan_task_has_user_user1` FOREIGN KEY (`id_user`) REFERENCES `user` (`id_user`) ON DELETE NO ACTION ON UPDATE NO ACTION
) ENGINE=InnoDB AUTO_INCREMENT=3605 DEFAULT CHARSET=utf8;
CREATE TABLE `alert_disable_rule` (
`id_alert_disable_rule` mediumint(9) NOT NULL AUTO_INCREMENT,
`disable_in_weekend` tinyint(1) DEFAULT '0',
`start_date` datetime DEFAULT NULL,
`end_date` datetime DEFAULT NULL,
`start_time` decimal(10,0) DEFAULT NULL,
`end_time` decimal(10,0) DEFAULT NULL,
PRIMARY KEY (`id_alert_disable_rule`)
) ENGINE=InnoDB DEFAULT CHARSET=utf8;
为了使外键约束成功，必须满足以下条件：
- 数据类型1和符号必须匹配
- 引用的 table 必须在相关列上有一个 left-most2 索引，以便快速进行约束验证。
- 整理可以起到一定的作用。请看我的
在你的情况下，索引很好，但正如 Solarflare 提到的，这里只有你的数据类型才是重要的 mis-matched:
`alert_disable_register`.`id_escalation_plan`-- signed int
`escalation_plan`.`id_escalation_plan` -- unsigned int
请注意，显示宽度（您在 parentheses 中的数字）和可空性无关紧要。
来自 Mysql 手册页 Using FOREIGN KEY Constraints:
Corresponding columns in the foreign key and the referenced key must
have similar data types. The size and sign of integer types must be
the same. The length of string types need not be the same. For
nonbinary (character) string columns, the character set and collation
must be the same.
MySQL requires indexes on foreign keys and referenced keys so that
foreign key checks can be fast and not require a table scan. In the
referencing table, there must be an index where the foreign key
columns are listed as the first columns in the same order.
Corresponding columns in the foreign key and the referenced key must
have similar data types. The size and sign of integer types must be
the same. The length of string types need not be the same. For
nonbinary (character) string columns, the character set and collation
must be the same.
还要注意，满足FK关系的referencedtable键不需要是Primary Key甚至Unique key。 first-most（也称为left-most2）在订购满足。
同样，索引不是您的问题，但通常是其他人的问题。
对于table创建后需要添加外键约束的，使用ALTER TABLE语句。
下面的测试 运行 没问题。不过，您需要自行决定如何处理更改。您遗漏了一些 tables 提供的内容，这需要在前 2 tables 中删除一些 FK 约束。
create database xyztest123;
use xyztest123;
CREATE TABLE `escalation_plan` (
`id_escalation_plan` int(10) unsigned NOT NULL AUTO_INCREMENT,
`id_indicator` mediumint(8) unsigned NOT NULL,
`id_label` mediumint(8) unsigned NOT NULL,
`pressure_waiting_hrs` int(11) NOT NULL DEFAULT '6',
PRIMARY KEY (`id_escalation_plan`),
KEY `fk_escalation_plan_escalation_plan1_idx` (`id_indicator`),
KEY `fk_escalation_plan_label1_idx` (`id_label`)
-- CONSTRAINT `fk_escalation_plan_escalation_plan1` FOREIGN KEY (`id_indicator`) REFERENCES `indicator` (`id_indicator`) ON DELETE NO ACTION ON UPDATE NO ACTION,
-- CONSTRAINT `fk_escalation_plan_label1` FOREIGN KEY (`id_label`) REFERENCES `label` (`id_label`) ON DELETE NO ACTION ON UPDATE NO ACTION
) ENGINE=InnoDB AUTO_INCREMENT=152 DEFAULT CHARSET=utf8;
CREATE TABLE `escalation_plan_task_group_has_user` (
`id_escalation_plan_task_has_user` int(10) unsigned NOT NULL AUTO_INCREMENT,
`id_user` mediumint(8) unsigned NOT NULL,
`id_escalation_plan_task_group` int(11) NOT NULL,
`text_alert` tinyint(1) NOT NULL DEFAULT '1',
`email_alert` tinyint(1) NOT NULL DEFAULT '1',
PRIMARY KEY (`id_escalation_plan_task_has_user`),
KEY `fk_escalation_plan_task_has_user_user1_idx` (`id_user`),
KEY `fk_escalation_plan_task_group_has_user_escalation_plan_task_idx` (`id_escalation_plan_task_group`)
-- CONSTRAINT `fk_escalation_plan_task_group_has_user_escalation_plan_task_g1` FOREIGN KEY (`id_escalation_plan_task_group`) REFERENCES `escalation_plan_task_group` (`id_escalation_plan_task_group`) ON DELETE NO ACTION ON UPDATE NO ACTION,
-- CONSTRAINT `fk_escalation_plan_task_has_user_user1` FOREIGN KEY (`id_user`) REFERENCES `user` (`id_user`) ON DELETE NO ACTION ON UPDATE NO ACTION
) ENGINE=InnoDB AUTO_INCREMENT=3605 DEFAULT CHARSET=utf8;
CREATE TABLE `alert_disable_rule` (
`id_alert_disable_rule` mediumint(9) NOT NULL AUTO_INCREMENT,
`disable_in_weekend` tinyint(1) DEFAULT '0',
`start_date` datetime DEFAULT NULL,
`end_date` datetime DEFAULT NULL,
`start_time` decimal(10,0) DEFAULT NULL,
`end_time` decimal(10,0) DEFAULT NULL,
PRIMARY KEY (`id_alert_disable_rule`)
) ENGINE=InnoDB DEFAULT CHARSET=utf8;
CREATE TABLE IF NOT EXISTS `alert_disable_register` (
`id_alert_disable_register` MEDIUMINT NOT NULL AUTO_INCREMENT,
`id_label` MEDIUMINT UNSIGNED NULL,
`id_indicator` MEDIUMINT UNSIGNED NULL,
`id_user` MEDIUMINT UNSIGNED NULL,
`active` TINYINT(1) NULL DEFAULT 1,
`id_alert_disable_rule` MEDIUMINT NULL,
`id_escalation_plan` INT unsigned NULL,
PRIMARY KEY (`id_alert_disable_register`),
INDEX `id_escalation_plan_alert_rule_idx` (`id_alert_disable_rule` ASC),
INDEX `id_label_idx` (`id_label` ASC),
INDEX `id_indicator_idx` (`id_indicator` ASC),
INDEX `id_user_idx` (`id_user` ASC),
INDEX `id_escalation_plan_idx` (`id_escalation_plan` ASC),
CONSTRAINT `id_label`
FOREIGN KEY (`id_label`) -- MEDIUMINT UNSIGNED
REFERENCES `escalation_plan` (`id_label`) -- mediumint(8) unsigned , -- Index OK?: Yes
ON DELETE NO ACTION
ON UPDATE NO ACTION,
CONSTRAINT `id_indicator`
FOREIGN KEY (`id_indicator`) -- MEDIUMINT UNSIGNED
REFERENCES `escalation_plan` (`id_indicator`) -- mediumint(8) unsigned, -- Index OK?: Yes
ON DELETE NO ACTION
ON UPDATE NO ACTION,
CONSTRAINT `id_user`
FOREIGN KEY (`id_user`) -- MEDIUMINT UNSIGNED
REFERENCES `escalation_plan_task_group_has_user` (`id_user`) -- mediumint(8) unsigned, -- Index OK?: Yes
ON DELETE NO ACTION
ON UPDATE NO ACTION,
CONSTRAINT `id_alert_disable_rule`
FOREIGN KEY (`id_alert_disable_rule`) -- MEDIUMINT
REFERENCES `alert_disable_rule` (`id_alert_disable_rule`) -- mediumint(9), -- Index OK?: Yes
ON DELETE SET NULL
ON UPDATE SET NULL,
CONSTRAINT `id_escalation_plan`
FOREIGN KEY (`id_escalation_plan`) -- INT
REFERENCES `escalation_plan` (`id_escalation_plan`) -- int(10) unsigned, Index OK?: Yes
ON DELETE NO ACTION
ON UPDATE NO ACTION)
ENGINE = InnoDB;
drop database xyztest123;
1 相似且允许的列差异，字符串数据
drop table if exists a2; -- must do in reverse order
drop table if exists a1;
create table a1
( id int auto_increment primary key,
thing varchar(100) not null,
key `keyname001` (thing)
)ENGINE = InnoDB;
create table a2
( id int auto_increment primary key,
myThing char(40) not null, -- similar and allowable datatype
foreign key `fk_002` (myThing) references a1(thing)
)ENGINE = InnoDB;
insert a2(myThing) values ('a'); -- error 1452, FK violation
insert a1(thing) values ('a'); -- ok
insert a2(myThing) values ('a'); -- ok, not FK violation
-- now a redo below to show it slightly different
drop table if exists a2; -- must do in reverse order
drop table if exists a1;
create table a1
( id int auto_increment primary key,
thing varchar(100) not null,
key `keyname001` (thing)
)ENGINE = InnoDB;
create table a2
( id int auto_increment primary key,
myThing varchar(30) not null, -- similar and allowable datatype
key(myThing),
foreign key `fk_002` (myThing) references a1(thing)
)ENGINE = InnoDB;
insert a2(myThing) values ('a'); -- error 1452, FK violation
insert a1(thing) values ('a'); -- ok
insert a2(myThing) values ('a'); -- ok, not FK violation
2 Left-most / First-most 指数排序
单个列上的索引（a.k.a。键）是left-most，因为它不是复合索引。
一个multi-column索引（a.k.a.一个复合索引）在一个parent（一个引用) table 是 left-most 如果其列的顺序与依赖于它的外键的 child table 键的顺序相同（FK ） 关系。即使 parent 复合键中的列数大于 child 复合键中的列数。请参阅下面的示例。
假设 child (referencing) table 具有按 (col1,col4) 然后
排序的复合键 FK 要求
由 (col1,col2,col3,col4) 排序的 parent 组合键不满足 left-most 要求。
由 (col1,col4,col3, ...) 排序的 parent 组合键确实满足 left-most 要求。
这里的take-away就是如果这样的parent键不left-most满足，那么声明为childtableCREATE TABLE FK 关系将失败。创建 table 的尝试将简单地失败，错误代码为 1215.
同样，存在的 child 的 ALTER TABLE 将在尝试添加 FK 关系 after-the-fact.
时失败
我想通过 运行 在 MySQL 中创建一个 table 跟随 SQL、
CREATE TABLE IF NOT EXISTS `shrewd_db`.`alert_disable_register` (
`id_alert_disable_register` MEDIUMINT NOT NULL AUTO_INCREMENT,
`id_label` MEDIUMINT UNSIGNED NULL,
`id_indicator` MEDIUMINT UNSIGNED NULL,
`id_user` MEDIUMINT UNSIGNED NULL,
`active` TINYINT(1) NULL DEFAULT 1,
`id_alert_disable_rule` MEDIUMINT NULL,
`id_escalation_plan` INT NULL,
PRIMARY KEY (`id_alert_disable_register`),
INDEX `id_escalation_plan_alert_rule_idx` (`id_alert_disable_rule` ASC),
INDEX `id_label_idx` (`id_label` ASC),
INDEX `id_indicator_idx` (`id_indicator` ASC),
INDEX `id_user_idx` (`id_user` ASC),
INDEX `id_escalation_plan_idx` (`id_escalation_plan` ASC),
CONSTRAINT `id_label`
FOREIGN KEY (`id_label`)
REFERENCES `shrewd_db`.`escalation_plan` (`id_label`)
ON DELETE NO ACTION
ON UPDATE NO ACTION,
CONSTRAINT `id_indicator`
FOREIGN KEY (`id_indicator`)
REFERENCES `shrewd_db`.`escalation_plan` (`id_indicator`)
ON DELETE NO ACTION
ON UPDATE NO ACTION,
CONSTRAINT `id_user`
FOREIGN KEY (`id_user`)
REFERENCES `shrewd_db`.`escalation_plan_task_group_has_user` (`id_user`)
ON DELETE NO ACTION
ON UPDATE NO ACTION,
CONSTRAINT `id_alert_disable_rule`
FOREIGN KEY (`id_alert_disable_rule`)
REFERENCES `shrewd_db`.`alert_disable_rule` (`id_alert_disable_rule`)
ON DELETE SET NULL
ON UPDATE SET NULL,
CONSTRAINT `id_escalation_plan`
FOREIGN KEY (`id_escalation_plan`)
REFERENCES `shrewd_db`.`escalation_plan` (`id_escalation_plan`)
ON DELETE NO ACTION
ON UPDATE NO ACTION)
ENGINE = InnoDB;
但我遇到以下错误，
ERROR 1005 (HY000): Can't create table 'shrewd_db.alert_disable_register' (errno: 150)
谁能帮我解决这个问题，:)
请在下面找到创建其他所需 table 的脚本，
CREATE TABLE `escalation_plan` (
`id_escalation_plan` int(10) unsigned NOT NULL AUTO_INCREMENT,
`id_indicator` mediumint(8) unsigned NOT NULL,
`id_label` mediumint(8) unsigned NOT NULL,
`pressure_waiting_hrs` int(11) NOT NULL DEFAULT '6',
PRIMARY KEY (`id_escalation_plan`),
KEY `fk_escalation_plan_escalation_plan1_idx` (`id_indicator`),
KEY `fk_escalation_plan_label1_idx` (`id_label`),
CONSTRAINT `fk_escalation_plan_escalation_plan1` FOREIGN KEY (`id_indicator`) REFERENCES `indicator` (`id_indicator`) ON DELETE NO ACTION ON UPDATE NO ACTION,
CONSTRAINT `fk_escalation_plan_label1` FOREIGN KEY (`id_label`) REFERENCES `label` (`id_label`) ON DELETE NO ACTION ON UPDATE NO ACTION
) ENGINE=InnoDB AUTO_INCREMENT=152 DEFAULT CHARSET=utf8;
CREATE TABLE `escalation_plan_task_group_has_user` (
`id_escalation_plan_task_has_user` int(10) unsigned NOT NULL AUTO_INCREMENT,
`id_user` mediumint(8) unsigned NOT NULL,
`id_escalation_plan_task_group` int(11) NOT NULL,
`text_alert` tinyint(1) NOT NULL DEFAULT '1',
`email_alert` tinyint(1) NOT NULL DEFAULT '1',
PRIMARY KEY (`id_escalation_plan_task_has_user`),
KEY `fk_escalation_plan_task_has_user_user1_idx` (`id_user`),
KEY `fk_escalation_plan_task_group_has_user_escalation_plan_task_idx` (`id_escalation_plan_task_group`),
CONSTRAINT `fk_escalation_plan_task_group_has_user_escalation_plan_task_g1` FOREIGN KEY (`id_escalation_plan_task_group`) REFERENCES `escalation_plan_task_group` (`id_escalation_plan_task_group`) ON DELETE NO ACTION ON UPDATE NO ACTION,
CONSTRAINT `fk_escalation_plan_task_has_user_user1` FOREIGN KEY (`id_user`) REFERENCES `user` (`id_user`) ON DELETE NO ACTION ON UPDATE NO ACTION
) ENGINE=InnoDB AUTO_INCREMENT=3605 DEFAULT CHARSET=utf8;
CREATE TABLE `alert_disable_rule` (
`id_alert_disable_rule` mediumint(9) NOT NULL AUTO_INCREMENT,
`disable_in_weekend` tinyint(1) DEFAULT '0',
`start_date` datetime DEFAULT NULL,
`end_date` datetime DEFAULT NULL,
`start_time` decimal(10,0) DEFAULT NULL,
`end_time` decimal(10,0) DEFAULT NULL,
PRIMARY KEY (`id_alert_disable_rule`)
) ENGINE=InnoDB DEFAULT CHARSET=utf8;
为了使外键约束成功，必须满足以下条件：
- 数据类型1和符号必须匹配
- 引用的 table 必须在相关列上有一个 left-most2 索引，以便快速进行约束验证。
- 整理可以起到一定的作用。请看我的
在你的情况下，索引很好，但正如 Solarflare 提到的，这里只有你的数据类型才是重要的 mis-matched:
`alert_disable_register`.`id_escalation_plan`-- signed int
`escalation_plan`.`id_escalation_plan` -- unsigned int
请注意，显示宽度（您在 parentheses 中的数字）和可空性无关紧要。
来自 Mysql 手册页 Using FOREIGN KEY Constraints:
Corresponding columns in the foreign key and the referenced key must have similar data types. The size and sign of integer types must be the same. The length of string types need not be the same. For nonbinary (character) string columns, the character set and collation must be the same.
MySQL requires indexes on foreign keys and referenced keys so that foreign key checks can be fast and not require a table scan. In the referencing table, there must be an index where the foreign key columns are listed as the first columns in the same order.
Corresponding columns in the foreign key and the referenced key must have similar data types. The size and sign of integer types must be the same. The length of string types need not be the same. For nonbinary (character) string columns, the character set and collation must be the same.
还要注意，满足FK关系的referencedtable键不需要是Primary Key甚至Unique key。 first-most（也称为left-most2）在订购满足。
同样，索引不是您的问题，但通常是其他人的问题。
对于table创建后需要添加外键约束的，使用ALTER TABLE语句。
下面的测试 运行 没问题。不过，您需要自行决定如何处理更改。您遗漏了一些 tables 提供的内容，这需要在前 2 tables 中删除一些 FK 约束。
create database xyztest123;
use xyztest123;
CREATE TABLE `escalation_plan` (
`id_escalation_plan` int(10) unsigned NOT NULL AUTO_INCREMENT,
`id_indicator` mediumint(8) unsigned NOT NULL,
`id_label` mediumint(8) unsigned NOT NULL,
`pressure_waiting_hrs` int(11) NOT NULL DEFAULT '6',
PRIMARY KEY (`id_escalation_plan`),
KEY `fk_escalation_plan_escalation_plan1_idx` (`id_indicator`),
KEY `fk_escalation_plan_label1_idx` (`id_label`)
-- CONSTRAINT `fk_escalation_plan_escalation_plan1` FOREIGN KEY (`id_indicator`) REFERENCES `indicator` (`id_indicator`) ON DELETE NO ACTION ON UPDATE NO ACTION,
-- CONSTRAINT `fk_escalation_plan_label1` FOREIGN KEY (`id_label`) REFERENCES `label` (`id_label`) ON DELETE NO ACTION ON UPDATE NO ACTION
) ENGINE=InnoDB AUTO_INCREMENT=152 DEFAULT CHARSET=utf8;
CREATE TABLE `escalation_plan_task_group_has_user` (
`id_escalation_plan_task_has_user` int(10) unsigned NOT NULL AUTO_INCREMENT,
`id_user` mediumint(8) unsigned NOT NULL,
`id_escalation_plan_task_group` int(11) NOT NULL,
`text_alert` tinyint(1) NOT NULL DEFAULT '1',
`email_alert` tinyint(1) NOT NULL DEFAULT '1',
PRIMARY KEY (`id_escalation_plan_task_has_user`),
KEY `fk_escalation_plan_task_has_user_user1_idx` (`id_user`),
KEY `fk_escalation_plan_task_group_has_user_escalation_plan_task_idx` (`id_escalation_plan_task_group`)
-- CONSTRAINT `fk_escalation_plan_task_group_has_user_escalation_plan_task_g1` FOREIGN KEY (`id_escalation_plan_task_group`) REFERENCES `escalation_plan_task_group` (`id_escalation_plan_task_group`) ON DELETE NO ACTION ON UPDATE NO ACTION,
-- CONSTRAINT `fk_escalation_plan_task_has_user_user1` FOREIGN KEY (`id_user`) REFERENCES `user` (`id_user`) ON DELETE NO ACTION ON UPDATE NO ACTION
) ENGINE=InnoDB AUTO_INCREMENT=3605 DEFAULT CHARSET=utf8;
CREATE TABLE `alert_disable_rule` (
`id_alert_disable_rule` mediumint(9) NOT NULL AUTO_INCREMENT,
`disable_in_weekend` tinyint(1) DEFAULT '0',
`start_date` datetime DEFAULT NULL,
`end_date` datetime DEFAULT NULL,
`start_time` decimal(10,0) DEFAULT NULL,
`end_time` decimal(10,0) DEFAULT NULL,
PRIMARY KEY (`id_alert_disable_rule`)
) ENGINE=InnoDB DEFAULT CHARSET=utf8;
CREATE TABLE IF NOT EXISTS `alert_disable_register` (
`id_alert_disable_register` MEDIUMINT NOT NULL AUTO_INCREMENT,
`id_label` MEDIUMINT UNSIGNED NULL,
`id_indicator` MEDIUMINT UNSIGNED NULL,
`id_user` MEDIUMINT UNSIGNED NULL,
`active` TINYINT(1) NULL DEFAULT 1,
`id_alert_disable_rule` MEDIUMINT NULL,
`id_escalation_plan` INT unsigned NULL,
PRIMARY KEY (`id_alert_disable_register`),
INDEX `id_escalation_plan_alert_rule_idx` (`id_alert_disable_rule` ASC),
INDEX `id_label_idx` (`id_label` ASC),
INDEX `id_indicator_idx` (`id_indicator` ASC),
INDEX `id_user_idx` (`id_user` ASC),
INDEX `id_escalation_plan_idx` (`id_escalation_plan` ASC),
CONSTRAINT `id_label`
FOREIGN KEY (`id_label`) -- MEDIUMINT UNSIGNED
REFERENCES `escalation_plan` (`id_label`) -- mediumint(8) unsigned , -- Index OK?: Yes
ON DELETE NO ACTION
ON UPDATE NO ACTION,
CONSTRAINT `id_indicator`
FOREIGN KEY (`id_indicator`) -- MEDIUMINT UNSIGNED
REFERENCES `escalation_plan` (`id_indicator`) -- mediumint(8) unsigned, -- Index OK?: Yes
ON DELETE NO ACTION
ON UPDATE NO ACTION,
CONSTRAINT `id_user`
FOREIGN KEY (`id_user`) -- MEDIUMINT UNSIGNED
REFERENCES `escalation_plan_task_group_has_user` (`id_user`) -- mediumint(8) unsigned, -- Index OK?: Yes
ON DELETE NO ACTION
ON UPDATE NO ACTION,
CONSTRAINT `id_alert_disable_rule`
FOREIGN KEY (`id_alert_disable_rule`) -- MEDIUMINT
REFERENCES `alert_disable_rule` (`id_alert_disable_rule`) -- mediumint(9), -- Index OK?: Yes
ON DELETE SET NULL
ON UPDATE SET NULL,
CONSTRAINT `id_escalation_plan`
FOREIGN KEY (`id_escalation_plan`) -- INT
REFERENCES `escalation_plan` (`id_escalation_plan`) -- int(10) unsigned, Index OK?: Yes
ON DELETE NO ACTION
ON UPDATE NO ACTION)
ENGINE = InnoDB;
drop database xyztest123;
1 相似且允许的列差异，字符串数据
drop table if exists a2; -- must do in reverse order
drop table if exists a1;
create table a1
( id int auto_increment primary key,
thing varchar(100) not null,
key `keyname001` (thing)
)ENGINE = InnoDB;
create table a2
( id int auto_increment primary key,
myThing char(40) not null, -- similar and allowable datatype
foreign key `fk_002` (myThing) references a1(thing)
)ENGINE = InnoDB;
insert a2(myThing) values ('a'); -- error 1452, FK violation
insert a1(thing) values ('a'); -- ok
insert a2(myThing) values ('a'); -- ok, not FK violation
-- now a redo below to show it slightly different
drop table if exists a2; -- must do in reverse order
drop table if exists a1;
create table a1
( id int auto_increment primary key,
thing varchar(100) not null,
key `keyname001` (thing)
)ENGINE = InnoDB;
create table a2
( id int auto_increment primary key,
myThing varchar(30) not null, -- similar and allowable datatype
key(myThing),
foreign key `fk_002` (myThing) references a1(thing)
)ENGINE = InnoDB;
insert a2(myThing) values ('a'); -- error 1452, FK violation
insert a1(thing) values ('a'); -- ok
insert a2(myThing) values ('a'); -- ok, not FK violation
2 Left-most / First-most 指数排序
单个列上的索引（a.k.a。键）是left-most，因为它不是复合索引。
一个multi-column索引（a.k.a.一个复合索引）在一个parent（一个引用) table 是 left-most 如果其列的顺序与依赖于它的外键的 child table 键的顺序相同（FK ） 关系。即使 parent 复合键中的列数大于 child 复合键中的列数。请参阅下面的示例。
假设 child (referencing) table 具有按 (col1,col4) 然后
由
(col1,col2,col3,col4)排序的 parent 组合键不满足 left-most 要求。由
(col1,col4,col3, ...)排序的 parent 组合键确实满足 left-most 要求。
这里的take-away就是如果这样的parent键不left-most满足，那么声明为childtableCREATE TABLE FK 关系将失败。创建 table 的尝试将简单地失败，错误代码为 1215.
同样，存在的 child 的 ALTER TABLE 将在尝试添加 FK 关系 after-the-fact.