#1215 - Cannot add foreign key constraint - php

Question

I'm working a project with Yiiframwork and I have this table in my data base project
CREATE TABLE IF NOT EXISTS `tbl_annonce` (
`id` mediumint(8) unsigned NOT NULL AUTO_INCREMENT,
`idEntreprise` tinyint(3) unsigned NOT NULL
COMMENT 'CONSTRAINT FOREIGN KEY (idEntreprise) REFERENCES tbl_entreprise(id)',
`titre` varchar(100) NOT NULL,
`detailleDiscription` varchar(5000) NOT NULL,
`categorie` varchar(100) DEFAULT NULL,
`typePoste` varchar(100) NOT NULL,
`salaireMin` varchar(80) NOT NULL,
`salaireMax` varchar(80) NOT NULL,
`niveauEtude` varchar(80) NOT NULL,
`niveauExperience` varchar(80) NOT NULL,
`langue` varchar(50) DEFAULT NULL,
`poste` varchar(50) NOT NULL,
`pays` varchar(50) NOT NULL,
`ville` varchar(50) NOT NULL,
`adresse` varchar(80) NOT NULL,
`datePublication` timestamp NOT NULL
DEFAULT CURRENT_TIMESTAMP ON UPDATE CURRENT_TIMESTAMP,
`etat` varchar(50) NOT NULL,
`photo` varchar(255) NULL,
`nometr` text NOT NULL,
PRIMARY KEY (`id`),
CONSTRAINT `fk_idEntrepriseAnn`
FOREIGN KEY (idEntreprise)
REFERENCES tbl_entreprise(id)
ON DELETE CASCADE ON UPDATE CASCADE
) ENGINE=InnoDB DEFAULT CHARSET=latin1 AUTO_INCREMENT=6 ;
I only use 'comment' because I found it in a tutorial for a yii framework project.
I have got the attribute 'idEntreprise' as FK in my DB but when I entred other 'idEntreprise' that does note exist in my table entreprise it was not problem, instead it must be a problem.
So I added 'identreprise' as Fk and that have this problem now.
Hope you understand my problem :/
can any one helep me plz !!

Answer 1

To define a foreign key on a column, it must fulfil some conditions.
Child and parent column must have same column definition by type,
signed.
Parent column must have an index defined on it.
Make sure that
The column tbl_entreprise.id is indexed.
The column definition idEntreprise tinyint(3) unsigned in tbl_annonce matches
with that of tbl_entreprise.id
Refer to: MySQL: Foregin Key Constaints