MySQL - 使用子查詢進行分組

Question

我遇到了子查詢和一些分組問題。子查詢從整個表中選擇，而不只是個別羣體的......我的代碼

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 

我的目標是有一個子查詢只返回的記錄數，其中即TIMEDIFF結果小於40中的特定間隔

謝謝。

Answer 1

我不認爲你需要這個子查詢。只要做到有條件聚集：

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; 

你可以使用子查詢獲得總數超過所有記錄，不會受到where子句或group by的人。