title: Unknown column in 'where clause' with stored procedure
body: <p>I am using a stored procedure with a prepared statment to find rows from a string of email addresses.</p>
  
  <p>It looks like this:</p>
  
  <p>DELIMITER $$</p>
  
  <pre><code>CREATE DEFINER=`root`@`localhost` PROCEDURE `get_users_by_email`(IN emailString VARCHAR(100))
  BEGIN
      SET @sql = CONCAT('SELECT user_id FROM users WHERE user_email IN  (',emailString,')');
      PREPARE qry FROM @sql;
      EXECUTE qry;
  END
  </code></pre>
  
  <p>I then call the procedure using:</p>
  
  <p><code>CALL get_users_by_email('me@email.com,you@email.com, etc..');</code></p>
  
  <p>But, I receive this error:</p>
  
  <p><code>Unknown column in 'me@email.com' in 'where clause'</code></p>
  
  <p>The query works if I use it to find numeric values such as:</p>
  
  <p><code>CALL get_users_by_email('123,456');</code></p>
  
  <p>Any ideas why it would be erroring on alphanumeric values? The query works fine when it is pulled out of the prepared statement and procedure.</p>