簡單的問題描述：

1. Django後臺配置的上海時間

2. postgresql採用了預設UTC時間

3. 後臺跟資料庫差了8個小時，頁面顯示沒得問題

4. 當通過orm執行原生SQL的時候發現按照小時統計的結果還是晚了八個小時

網上找了很多教程，有讓改postgresql配置檔案，timezone改為PRC。改完之後資料庫顯示沒問題。但是通過SQL分組查詢還是會有問題

SELECT
  (to_char(take_photo_time, 'yyyy-mm-dd:HH')) AS "take_photo_time",
  COUNT(take_photo_time) AS "count"
 
FROM
  "device_devicephotomodel"
WHERE
  "device_devicephotomodel".take_photo_time BETWEEN '2020-12-23T00:00:00' :: TIMESTAMP
  AND '2020-12-24T00:00:00' :: TIMESTAMP
GROUP BY
  (to_char(take_photo_time, 'yyyy-mm-dd:HH'))
ORDER BY
  "take_photo_time" DESC;

統計到的結果，依然是晚了8個小時

通過date_trunte可以解決。但是還得調整介面，太麻煩

SELECT
    DATE_TRUNC( 
 
'HOUR', take_photo_time ) AS "take_photo_time",
    COUNT ( take_photo_time ) AS "count" 
FROM
    "device_devicephotomodel" 
WHERE
    "device_devicephotomodel".take_photo_time BETWEEN '2020-12-23T00:00:00' :: TIMESTAMP 
    AND '2020-12-24T00:00:00' :: TIMESTAMP 
GROUP BY
    (
    DATE_TRUNC('HOUR', take_photo_time))
 
ORDER BY
    "take_photo_time" DESC;

於是找了一些比較官方的文件，說是需要·····················。。直接貼解決方式

SELECT
  (to_char(take_photo_time, 'yyyy-mm-dd:HH24')) AS "take_photo_time",
  COUNT(take_photo_time) AS "count"
FROM
  "device_devicephotomodel"
WHERE
  "device_devicephotomodel".take_photo_time BETWEEN '2020-12-23T00:00:00' :: TIMESTAMP
  AND '2020-12-24T00:00:00' :: TIMESTAMP
GROUP BY
  (to_char(take_photo_time, 'yyyy-mm-dd:HH24'))
ORDER BY
  "take_photo_time" DESC;

上邊飄紅的地方，就是重點。兩個數字解決了一天·····有點無語

最後發現。正確了。滿足我的需求了。。可以回家了