MySQL - 使用子查询进行分组

Question

我遇到了子查询和一些分组问题。子查询从整个表中选择，而不只是个别群体的......我的代码

SELECT SEC_TO_TIME(TIME_TO_SEC(call_start) - TIME_TO_SEC(call_start)%(30*60)) AS intervals, 
     COUNT(*) AS OFFERED, 
     SUM(agent_duration) AS AGENT_SUM, 
     SUM(TIME_TO_SEC(TIMEDIFF(dequeue_time, enqueue_time))) AS ANS_TIME_SUM, 
     COUNT(DISTINCT agent_username) AS UNIQUE_AGENTS, 
     (SELECT COUNT(*) FROM call_detail 
     WHERE TIME_TO_SEC(TIMEDIFF(dequeue_time, enqueue_time)) < 40) AS SLA, 
     SUM(queue_duration) AS TOTAL_QUEUE_TIME 
FROM call_detail 
WHERE DATE(call_start) = CURDATE() 
GROUP BY intervals 

我的目标是有一个子查询只返回的记录数，其中即TIMEDIFF结果小于40中的特定间隔

谢谢。

Answer 1

我不认为你需要这个子查询。只要做到有条件聚集：

SELECT SEC_TO_TIME(TIME_TO_SEC(call_start) - TIME_TO_SEC(call_start)%(30*60)) AS intervals, 
     COUNT(*) AS OFFERED, 
     SUM(agent_duration) AS AGENT_SUM, 
     SUM(TIME_TO_SEC(TIMEDIFF(dequeue_time, enqueue_time))) AS ANS_TIME_SUM, 
     COUNT(DISTINCT agent_username) AS UNIQUE_AGENTS, 
     sum(case when TIME_TO_SEC(TIMEDIFF(dequeue_time, enqueue_time)) < 40 then 1 else 0 end) as SLA, 
     SUM(queue_duration) AS TOTAL_QUEUE_TIME 
FROM call_detail 
WHERE DATE(call_start) = CURDATE() 
GROUP BY intervals; 

你可以使用子查询获得总数超过所有记录，不会受到where子句或group by的人。