title: MySQL : Cannot add or update a child row: a foreign key constraint fails
body: <p>I got error :</p>
  
  <blockquote>
    <p>Cannot add or update a child row: a foreign key constraint fails</p>
  </blockquote>
  
  <p>This is my Insert query:</p>
  
  <pre><code>INSERT INTO `swat` (`Category`, `Importance_JK`, `MaxStrength`, `Person_id`, `SWAT_id`, `Strength`, `cost`, `date_Complete`, `due_Date`, `storage_id`, `updated`, `user_FK`) 
      VALUES ('1','2','we1','546','46','we','500','2016-04-19','2016-04-18','','2016-04-18','37')
  </code></pre>
  
  <p>If i print this query in SQL, then this MySql error occurs:</p>
  
  <blockquote>
    <p>#1452 - Cannot add or update a child row: a foreign key constraint fails (`sidemoin_crucialstuff`.`swat`, CONSTRAINT `swat_ibfk_3` FOREIGN KEY (`Person_id`) REFERENCES `key_people` (`Key_Person_ID`)) </p>
  </blockquote>
  
  <p>Any help please?</p>