title: I want to add an foreign key but everytime i try adding one i get error codes
body: <p>Coding that i used to altar my table and change it.</p>
  <pre><code>ALTER TABLE `the-challenge`.`klant` 
  ADD CONSTRAINT `resultaat`
    FOREIGN KEY (`resultaatid`)
    REFERENCES `the-challenge`.`resultaat` (`id`)
    ON DELETE NO ACTION
    ON UPDATE NO ACTION;
  </code></pre>
  <p>The results when trying to apply the code:
  Operation failed: There was an error while applying the SQL script to the database.
  Executing:</p>
  <pre><code>ALTER TABLE `the-challenge`.`klant` 
  ADD CONSTRAINT `resultaat`
    FOREIGN KEY (`resultaatid`)
    REFERENCES `the-challenge`.`resultaat` (`id`)
    ON DELETE NO ACTION
    ON UPDATE NO ACTION;
  </code></pre>
  <blockquote>
  <p>ERROR 1826: Duplicate foreign key constraint name 'resultaat'</p>
  </blockquote>
  <p>SQL Statement:</p>
  <pre><code>ALTER TABLE `the-challenge`.`klant` 
  ADD CONSTRAINT `resultaat`
    FOREIGN KEY (`resultaatid`)
    REFERENCES `the-challenge`.`resultaat` (`id`)
    ON DELETE NO ACTION
    ON UPDATE NO ACTION
  </code></pre>