title: SQL problem with subquery
body: <p>I get the following error while running this query:</p>
  
  <blockquote>
    <p>#1241 - Operand should contain 1 column(s)</p>
  </blockquote>
  
  <pre><code>SELECT *,
         Date_format(date_assigned, '%d-%m-%y')                     AS datum,
         YEAR(date_assigned)                                        AS YEAR,
         YEAR(NOW())                                                AS this_year,
         Datediff(NOW(), date_assigned)                             AS age,
         MONTH(NOW())                                               AS this_month,
         Concat(Period_add(Date_format(date_released, "%Y%m"), -6)) AS cancel_date
         ,
         Date_format(NOW(), '%Y%m')                                 AS
         this_date
  FROM   reseller_numbers
  WHERE  reseller_id = '31'
         AND MONTH(date_assigned) = '12'
         AND ( ( date_released IS NULL
                  OR date_released &gt; NOW() )
                OR ( Dayofyear(date_assigned) &lt;= Dayofyear(date_released)
                     AND ( date_released IS NULL
                            OR date_released &gt; NOW() ) ) )
         AND ( date_released IS NULL
                OR date_released &gt; NOW()
                   AND date_released NOT LIKE '%2999%'
                   AND date_released != '2038-01-01 00:00:00' )
         AND ( date_released NOT IN (SELECT *,
                                            Date_format(DATE_ADD(date_released,
                                                        INTERVAL '-6' MONTH),
                                            '%d%m%y')
                                            AS
                                            cancel_date
                                     FROM   reseller_numbers
                                     WHERE  reseller_id = '31'
                                     HAVING DATE_ADD(date_released,
                                            INTERVAL '-6' MONTH)
                                            &lt;
                                            NOW(
                                            )) )
  ORDER  BY date_released DESC
  LIMIT  0, 30 
  </code></pre>
  
  <p>Is there something wrong with this query? When I remove the subquery in date_released NOT IN, the query executes just fine.</p>