MySQL外键约束

Question

I'm having some issues with a foreign key constraint, and am probably not putting the code together properly.

The idea is that the airports table will only accept a type value that is in the apType table. If the type is not in the apType table, it should generate an error. However, I have been testing this and I am unable to get it to generate an error, it just places the type entered into the database and is happy with it.

Airport Table:

 CREATE TABLE `airport`(
`id` int primary key AUTO_INCREMENT,
`name` varchar(255) NOT NULL,
`rwyCount` int,
`lat` float(6),
`lon` float(6),
`type` varchar(255), 
constraint FOREIGN KEY (type) REFERENCES apType(type) match simple
)ENGINE=MyISAM DEFAULT CHARSET=latin1;

apType Table:

CREATE TABLE `apType`(
`id` int primary key AUTO_INCREMENT,
`type` varchar(255) NOT NULL
 )ENGINE=MyISAM DEFAULT CHARSET=latin1;

insert of values for apType (these are the only values that should be valid):

INSERT INTO `apType` (`type`) VALUES ('private'),('public'),('military');

Insert that should generate an error:

 insert into `airport` (`name` , `rwyCount` , `type` , `lat` , `lon`) values ('failland', 3 , 'space', 45.588611, -122.5975);

Can anyone figure out this issue?

Answer 1

It appears that foreign keys have not yet been implemented in the DB engine that you are using. Why doesn't MySQL's MyISAM engine support Foreign keys?

Maybe consider switching to InnoDb?