php - 显示 MySQL 表中不存在另一行的行

Question

我的 MySQL 数据库中有一个包含列的表:

• callid
• 事件

我想选择事件为“ENTERQUEUE”的所有行:

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

但是我想显示所有其他行，其中 'callid' 等于上述查询的结果(对于上述查询中返回的每一行)AND 没有行事件等于“CONNECT”。

Answer 1

您可以使用带有 NOT EXISTS 运算符的子查询:

SELECT   AVG(arg1) AS avg_hold_time 
FROM     ast_queue_log aql
WHERE    queuename = '0536*401' AND
         DATE(time) = '2014-03-07' AND
         event = 'ENTERQUEUE' AND
         NOT EXISTS (SELECT cnt.callid
                     FROM   ast_queueu_log cnt
                     WHERE  -- Same conditions as the surrounding query
                            queuename = '0536*401' AND
                            DATE(time) = '2014-03-07' AND
                            event = 'CONNECT' AND
                            -- matching callids
                            cnt.callid = aql.callid)
ORDER BY time DESC