mysql - Error during the creation of table due to foreign key -


i have table1 in db.

table1: 

create table `product` (   `id` int(11) not null auto_increment,   `typename` varchar(255) default null,   `typecode` varchar(55) default null,   `parent1` int(11) default null,   `parent2` int(11) default null,   primary key (`id`),   key `parent1` (`parent1`),   key `parent2` (`parent2`) ) engine=innodb auto_increment=396 default charset=latin1;

i tried create second table foreign key has reference product.typename

this creation query have used.

 create table measurements (     id int(11) not null auto_increment primary key,     age_group varchar(20) not null,     article_type varchar(255) default null,     dimension text ,     createdon int(11) not null,     updatedon int(11) not null,     createdby text not null,     foreign key(article_type) references product(typename) )engine=innodb auto_increment=396 default charset=latin1;

but table creation failure following error.

error 1215 (hy000): cannot add foreign key constraint

i have done show engine innodb\g

------------------------ latest foreign key error ------------------------ 2015-05-15 19:03:28 131f71000 error in foreign key constraint of table db/measurements: foreign key(article_type) references product(typename) )engine=innodb auto_increment=396 default charset=latin1: cannot find index in referenced table referenced columns appear first columns, or column types in table , referenced table not match constraint. note internal storage type of enum , set changed in tables created >= innodb-4.1.12, , such columns in old tables cannot referenced such columns in new tables. see http://dev.mysql.com/doc/refman/5.6/en/innodb-foreign-key-constraints.html correct foreign key definition.

can 1 point me problem , first columns concept?

referenced column should primary key. here 

foreign key(article_type) references product(typename)

you want reference typename column not pk.

to in way should create table producttype this:

create table `producttype` (   `id` int(11) not null auto_increment,   `typename` varchar(255) default null,   `typecode` varchar(55) default null, ) engine=innodb auto_increment=396 default charset=latin1;

then can create reference this:

 create table measurements (     id int(11) not null auto_increment primary key,     age_group varchar(20) not null,     idproducttype not null,     dimension text ,     createdon int(11) not null,     updatedon int(11) not null,     createdby text not null,     foreign key(idproducttype) references producttype(id) )engine=innodb auto_increment=396 default charset=latin1;

don't forget product table. above solution suggestion, have consider table structure yourself.


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