SQLSTATE[23000]: Integrity constraint violation: 1452 Cannot add or update a child row: a foreign key constraint fails

Question

I am trying to insert values into my comments table and I am getting a error. Its saying that I can not add or update child row and I have no idea what that means. My schema looks something like this:

--
-- Baza danych: `koxu1996_test`
--

-- --------------------------------------------------------

--
-- Struktura tabeli dla tabeli `user`
--

CREATE TABLE IF NOT EXISTS `user` (
  `id` int(8) NOT NULL AUTO_INCREMENT,
  `username` varchar(32) COLLATE utf8_bin NOT NULL,
  `password` varchar(64) COLLATE utf8_bin NOT NULL,
  `password_real` char(32) COLLATE utf8_bin NOT NULL,
  `email` varchar(32) COLLATE utf8_bin NOT NULL,
  `code` char(8) COLLATE utf8_bin NOT NULL,
  `activated` enum('0','1') COLLATE utf8_bin NOT NULL DEFAULT '0',
  `activation_key` char(32) COLLATE utf8_bin NOT NULL,
  `reset_key` varchar(32) COLLATE utf8_bin NOT NULL,
  `name` varchar(32) COLLATE utf8_bin NOT NULL,
  `street` varchar(32) COLLATE utf8_bin NOT NULL,
  `house_number` varchar(32) COLLATE utf8_bin NOT NULL,
  `apartment_number` varchar(32) COLLATE utf8_bin NOT NULL,
  `city` varchar(32) COLLATE utf8_bin NOT NULL,
  `zip_code` varchar(32) COLLATE utf8_bin NOT NULL,
  `phone_number` varchar(16) COLLATE utf8_bin NOT NULL,
  `country` int(8) NOT NULL,
  `province` int(8) NOT NULL,
  `pesel` varchar(32) COLLATE utf8_bin NOT NULL,
  `register_time` timestamp NOT NULL DEFAULT CURRENT_TIMESTAMP,
  `authorised_time` datetime NOT NULL,
  `edit_time` datetime NOT NULL,
  `saldo` decimal(9,2) NOT NULL,
  `referer_id` int(8) NOT NULL,
  `level` int(8) NOT NULL,
  PRIMARY KEY (`id`),
  KEY `country` (`country`),
  KEY `province` (`province`),
  KEY `referer_id` (`referer_id`)
) ENGINE=InnoDB  DEFAULT CHARSET=utf8 COLLATE=utf8_bin AUTO_INCREMENT=83 ;

and the mysql statement I am trying to do looks something like this:

INSERT INTO `user` (`password`, `code`, `activation_key`, `reset_key`, `register_time`,                `edit_time`, `saldo`, `referer_id`, `level`) VALUES (:yp0, :yp1, :yp2, :yp3, NOW(), NOW(), :yp4, :yp5, :yp6). Bound with :yp0='fa1269ea0d8c8723b5734305e48f7d46', :yp1='F154', :yp2='adc53c85bb2982e4b719470d3c247973', :yp3='', :yp4='0', :yp5=0, :yp6=1

the error I get looks like this:

SQLSTATE[23000]: Integrity constraint violation: 1452 Cannot add or update a child row: a foreign key constraint fails (koxu1996_test.user, CONSTRAINT user_ibfk_1 FOREIGN KEY (country) REFERENCES country_type (id) ON DELETE NO ACTION ON UPDATE NO ACTION)

Answer 1

It just simply means that the value for column country on table comments you are inserting doesn't exist on table country_type or you are not inserting value for country on table user. Bear in mind that the values of column country on table comments is dependent on the values of ID on table country_type.

Answer 2

You have foreign keys between this table and another table and that new row would violate that constraint.

You should be able to see the constraint if you run show create table user, it shows up as CONSTRAINT... and it shows what columns reference what tables/columns.

In this case country references country_type (id) and you are not specifying the value of country. You need to put a value that exists in country_type.