表的SELECT计数，其中列为CONNECT，但与其他相关列相关的其他行没有特定值

Question

I have a table in my MySQL database which has columns:

• callid
• event

I want to select all rows where the event is 'ENTERQUEUE' which i am doing in the below query:

SELECT count(*)
FROM voipnow.ast_queue_log
WHERE queuename = '0536*401'
  AND DATE(time) = '2014-03-07'
  AND event = 'ENTERQUEUE'
ORDER BY time DESC;

But i only want to show the number of rows where the event column is not equal to CONNECT where callid is equal to the callid column from the above query

Answer 1

Try:

SELECT count(*)
  FROM voipnow.ast_queue_log
 WHERE queuename = '0536*401'
   AND DATE(time) = '2014-03-07'
   AND event <> 'CONNECT'
   and callid not in (SELECT callid
                        FROM voipnow.ast_queue_log
                       WHERE queuename = '0536*401'
                         AND DATE(time) = '2014-03-07'
                         AND event = 'ENTERQUEUE')
 ORDER BY time DESC;

Answer 2

Your description leaves room for interpretation. I read it as:
"where no row exists with the same callid and event = 'CONNECT'"

SELECT count(*)
FROM   voipnow.ast_queue_log v1
WHERE  queuename = '0536*401'
AND    date(time) = '2014-03-07'
AND    event = 'ENTERQUEUE'
AND NOT EXISTS (
   SELECT 1
   FROM   voipnow.ast_queue_log v2
   WHERE  v2.callid = v1.callid 
   AND    v2.event = 'CONNECT'
   )