如何獲取 PostgreSQL 中的最新記錄？

Question

實際上我正在嘗試通過r_id和最新的start_date獲取這些數據的最新記錄

我的樣本數據：

**r_id**   **s_id **     **start_date**                               
"149165"    "28317"   "2020-09-07 08:12:46.108"                      
"149165"    "28324"   "2020-09-07 08:18:15.934"                     
"149161"    "28313"   "2020-09-07 08:11:33.923"      
"149161"    "28316"   "2020-09-07 08:12:19.887"                  
"149161"    "28312"   "2020-09-07 08:11:04.448"                  
"149161"    "28305"   "2020-09-07 08:09:17.211"                  

預期成績 ：

    **r_id**   **s_id **     **start_date**                                
    "149165"    "28324"   "2020-09-07 08:18:15.934"                  
    "149161"    "28316"   "2020-09-07 08:12:19.887"              

任何人請。

Answer 1

您可以使用distinct on ：

select distinct on (r_id) t.*
from mytable t
order by r_id, start_date desc