Question

I have a problem creating a foreign key constraint between two tables.

Here is the first table:

CREATE TABLE `agews_rifiuti_cer` (
  `id_cer` int(10) unsigned NOT NULL AUTO_INCREMENT,
  `agews_id` int(10) unsigned DEFAULT '0',
  `livello` tinyint(4) DEFAULT '1',
  `codice` varchar(10) DEFAULT NULL,
  `descrizione` varchar(255) DEFAULT NULL,
  `note` text,
  `flag_pericoloso` tinyint(1) DEFAULT '0',
  `id_cliente` int(10) unsigned DEFAULT '1',
  `flag_modificato` char(1) DEFAULT 'N',
  PRIMARY KEY (`id_cer`),
  KEY `fk_id_cliente_agews_sgs_codici_cer` (`id_cliente`)
) ENGINE=InnoDB  DEFAULT CHARSET=utf8;

And here is the second one:

CREATE TABLE `lin_98_47_rifiuti` (
  `id_rifiuto` int(10) unsigned NOT NULL AUTO_INCREMENT,
  `id_azienda` int(10) unsigned NOT NULL DEFAULT '1',
  `id_sede` int(10) unsigned NOT NULL DEFAULT '1',
  `revisione_documento` int(10) unsigned NOT NULL DEFAULT '0',
  `rifiuto` varchar(255) DEFAULT NULL,
  `codice_cer` varchar(10) DEFAULT NULL,
  `nome_interno` varchar(255) DEFAULT NULL,
  `descrizione` text,
  `materie_prime` text,
  `contenitore` text,
  `deposito` text,
  `data_ultima_analisi` date DEFAULT NULL,
  `stato_fisico` enum('Solido pulverulento','Solido non pulverulento','Fangoso palabile','Liquido') DEFAULT 'Solido non pulverulento',
  `quantita` float(9,1) DEFAULT '0.0',
  `unita_misura` enum('Kg','l','mc') DEFAULT 'Kg',
  `id_pericolo` int(10) unsigned DEFAULT NULL,
  `destino` enum('Recupero','Smaltimento') DEFAULT NULL,
  `id_recupero` int(10) unsigned DEFAULT NULL,
  `id_smaltimento` int(10) unsigned DEFAULT NULL,
  `id_cer` int(10) unsigned DEFAULT NULL,
  `immagine` varchar(255) DEFAULT NULL,
  `image_type` varchar(20) DEFAULT NULL,
  `image_content` mediumblob,
  `image_size_x` smallint(5) unsigned DEFAULT '0',
  `image_size_y` smallint(5) unsigned DEFAULT '0',
  `flag_storico` tinyint(1) DEFAULT '0',
  `id_responsabile` int(10) unsigned DEFAULT '0',
  `nome_responsabile` varchar(255) DEFAULT '0',
  `id_ultima_modifica` int(10) unsigned DEFAULT '0',
  `create_log` tinyint(1) DEFAULT '1',
  PRIMARY KEY (`id_rifiuto`,`id_azienda`,`id_sede`,`revisione_documento`),
  KEY `fk_main_lin_98_47_rifiuti` (`id_azienda`,`id_sede`,`revisione_documento`),
  KEY `fk_id_responsabile_lin_98_47_rifiuti` (`id_responsabile`,`id_azienda`,`id_sede`,`revisione_documento`,`nome_responsabile`),
  KEY `fk_id_pericolo_lin_98_47_rifiuti` (`id_pericolo`),
  KEY `fk_id_recupero_lin_98_47_rifiuti` (`id_recupero`),
  KEY `fk_id_smaltimento_lin_98_47_rifiuti` (`id_smaltimento`)
) ENGINE=InnoDB  DEFAULT CHARSET=utf8;

The problem happens the I try to do this:

ALTER TABLE lin_98_47_rifiuti ADD CONSTRAINT fk_id_cer_lin_98_47_rifiuti FOREIGN KEY (id_cer) REFERENCES agews_rifiuti_cer(id_cer) ON UPDATE CASCADE ON DELETE CASCADE;

And I get this error:

#1005 - Can't create table 'db_626suite.#sql-71c_13d5' (errno: 150)

While the command SHOW INNODB STATUS says:

Error in foreign key constraint of table db_626suite/#sql-71c_13d5:
 FOREIGN KEY (id_cer) REFERENCES agews_rifiuti_cer(id_cer) ON UPDATE CASCADE ON DELETE CASCADE:
Cannot resolve column name close to:
) ON UPDATE CASCADE ON DELETE CASCADE

But the syntax and fields definitions seem correct to me. What am I doing wrong?

EDIT:

Marc B suggested that it could be due to the fact that id_cer is defined as NOT NULL in agews_rifiuti_cer, but I do not think this is the case, in fact please consider this other table:

CREATE TABLE `agews_rifiuti_pericolo` (
  `id_pericolo` int(10) unsigned NOT NULL AUTO_INCREMENT,
  `agews_id` int(10) unsigned DEFAULT '0',
  `codice` varchar(255) DEFAULT NULL,
  `pericolo` varchar(255) DEFAULT NULL,
  `note` text,
  `id_cliente` int(10) unsigned DEFAULT '1',
  `flag_modificato` char(1) DEFAULT 'N',
  PRIMARY KEY (`id_pericolo`),
  KEY `codice_rifiuti_recupero` (`codice`),
  KEY `fk_id_cliente_rifiuti_pericolo` (`id_cliente`)
) ENGINE=InnoDB DEFAULT CHARSET=utf8;

Here id_pericolo is defined as NOT NULL as id_cer above, and yet this works perfectly:

ALTER TABLE lin_98_47_rifiuti ADD CONSTRAINT fk_id_pericolo_lin_98_47_rifiuti FOREIGN KEY (id_pericolo) REFERENCES agews_rifiuti_pericolo(id_pericolo) ON UPDATE CASCADE ON DELETE SET NULL;

even if in lin_98_47_rifiuti the field id_pericolo is defined as DEFAULT NULL

EDIT 2:

I just tried this minimal setup:

CREATE TABLE `cer` (
  `id_cer` int(10) unsigned NOT NULL AUTO_INCREMENT,
  `codice` varchar(10) DEFAULT NULL,
  PRIMARY KEY (`id_cer`)
) ENGINE=InnoDB  DEFAULT CHARSET=utf8;

CREATE TABLE `rifiuti` (
  `id_rifiuto` int(10) unsigned NOT NULL AUTO_INCREMENT,
  `id_cer` int(10) unsigned NULL DEFAULT NULL,
  `rifiuto` varchar(10) DEFAULT NULL,
  PRIMARY KEY (`id_rifiuto`)
) ENGINE=InnoDB  DEFAULT CHARSET=utf8;

ALTER TABLE rifiuti ADD FOREIGN KEY (id_cer) REFERENCES cer(id_cer) ON UPDATE CASCADE ON DELETE CASCADE;

and it all worked correctly, yet I do not understand what the problem might be in my original query.

Also I think this proves that is not a matter of defining the fields as NOT NULL or DEFAULT NULL.

Answer 1

I really do not understand why, but renaming id_cer to id_codice in all tables, while leaving its definition unaltered, has solved the problem.

So it would seem that MySQL had some kind of problem with that specific field name.