title: Error while writing socket code for creating quiz
body: <pre><code> code: 'ER_NO_REFERENCED_ROW_2',
  </code></pre>
  <p>errno: 1452,
  sqlMessage: 'Cannot add or update a child row: a foreign key constraint fails (<code>databasename</code>.<code>quizzes_player_1_id_links</code>, CONSTRAINT <code>quizzes_player_1_id_links_inv_fk</code> FOREIGN KEY (<code>user_id</code>) REFERENCES <code>up_users</code> (<code>id</code>) ON DELETE CASCADE)',
  sqlState: '23000',
  index: 0,
  sql: 'insert into <code>quizzes_player_1_id_links</code> (<code>quiz_id</code>, <code>user_id</code>) values (1, 1)'</p>
  <p>Can anyone tell me what is the error about? How to fix this?</p>