title: MySQL: Cannot delete or update a parent row: a foreign key constraint fails
body: <p>Hi i am trying to make simple database with 2 tables, first for user information, and second for their uploads, because it's project for faculty, i have some assignments... And one is to use foreign key.</p>
  
  <pre><code>DROP TABLE IF EXISTS `korisnici`;
  
  CREATE TABLE `korisnici` (
    `UserID` INT(11) NOT NULL AUTO_INCREMENT,
    `username` VARCHAR(12) NOT NULL,
    `password` VARCHAR(32) NOT NULL,
    `email` VARCHAR(32) NOT NULL,
    `telefon` VARCHAR(16) NOT NULL,
    PRIMARY KEY (`UserID`)
  );
  
  DROP TABLE IF EXISTS `slike`;
  
  CREATE TABLE `slike` (
    `id` INT(11) NOT NULL AUTO_INCREMENT,
    `name` VARCHAR(200) NOT NULL,
    `size` INTEGER(11) NOT NULL,
    `type` VARCHAR(200) NULL,
    `file_path` VARCHAR(200) NOT NULL,
    `username` VARCHAR(12) NOT NULL,
    `naslov` VARCHAR(32) NOT NULL,
    `adresa` VARCHAR(80) NOT NULL,
    `opis` VARCHAR(1200) NOT NULL,
    `datum` DATE NOT NULL,
    `UserID` INTEGER(11) NOT NULL,
    PRIMARY KEY (`id`)
  );
  
  ALTER TABLE `slike` ADD FOREIGN KEY (UserID) REFERENCES `korisnici` (`UserID`);
  
  
  -- ALTER TABLE `korisnici` ENGINE=InnoDB DEFAULT CHARSET=utf8 COLLATE=utf8_bin;
  -- ALTER TABLE `slike` ENGINE=InnoDB DEFAULT CHARSET=utf8 COLLATE=utf8_bin;
  
  
  
  -- ---
  -- Test Data
  -- ---
  
  INSERT INTO `korisnici` (`UserID`,`username`,`password`,`email`,`telefon`) VALUES('1','dd','d','d','d');
  INSERT INTO `slike` (`id`,`name`,`size`,`type`,`file_path`,`username`,`naslov`,`adresa`,`opis`,`datum`,`UserID`) VALUES('2','a','122','png','ksks/sss','dsss','aaaa','sss','ssss','2014/09/04','2');
  </code></pre>
  
  <p>ERROR:</p>
  
  <pre><code>ERROR 1217 (23000) at line 14: Cannot delete or update a parent row: a foreign key constraint fails
  </code></pre>
  
  <p>Anybody now where is the probel and how could i fix it? It also doesn't work on sqlfiddle when i insert some values for testing.
  Thanks :)</p>