Postgres的最小/最大

Question

您好我有一个表名令牌这将有这样

id  | generated_time   | token_name 
461087 | 2016-10-21 09:02:53.951 | G1 
461088 | 2016-10-21 09:31:13.469 | C1 
461089 | 2016-10-21 09:31:15.711 | C2 
461090 | 2016-10-21 10:37:17.73 | C3 
461091 | 2016-10-21 10:02:53.951 | G2 
461092 | 2016-10-21 10:15:13.469 | C4 
461093 | 2016-10-21 11:22:15.611 | C5 
461094 | 2016-10-21 11:31:14.743 | C6 

和表token_queue像这样具有以一对一的关系

serving_end_time  | serving_start_time  | token_id 
2016-10-21 09:04:45.681 | 2016-10-21 09:03:49.05 | 461087 
2016-10-21 09:33:49.035 | 2016-10-21 09:32:07.996 | 461088 
2016-10-21 09:34:42.431 | 2016-10-21 09:32:27.134 | 461089 
2016-10-21 10:39:57.775 | 2016-10-21 10:38:37.428 | 461090 
2016-10-21 10:04:49.715 | 2016-10-21 10:03:09.972 | 461091 
2016-10-21 10:17:28.268 | 2016-10-21 10:16:06.946 | 461092 
2016-10-21 11:23:36.036 | 2016-10-21 11:22:30.233 | 461093 
2016-10-21 11:32:32.876 | 2016-10-21 11:31:27.044 | 461094 

生成的令牌的数据现在我想从令牌表中以小时为单位显示全天的最小/最大值-24小时（current_date），并根据token_queue计算最小/最大值，即

MIN(token_queue.serving_end_time - token_queue.serving_start_time)
MAX(token_queue.serving_end_time - token_queue.serving_start_time)

这里是日期2016年10月21日

hour    | min   | max 
    2016-10-21 09:00:00 | 00:01:06 | 00:05:00 
    2016-10-21 10:00:00 | 00:01:16 | 00:04:00 
    2016-10-21 11:00:00 | 00:02:00 | 00:05:26 

感谢您的任何帮助/建议采样输出。

Answer 1

SELECT date_trunc('hour', t.generated_time) AS hour, 
     min(tq.serving_end_time - tq.serving_start_time) AS min, 
     max(tq.serving_end_time - tq.serving_start_time) AS max 
FROM token t 
    JOIN token_queue tq 
     ON t.id = tq.token_id 
GROUP BY 1 
ORDER BY 1;