查詢來獲取當前日期和最小日期爲ID

Question

我寫了這個SQL query.It不工作之間的區別，它說

從關鍵字未找到其中預期不會

在哪裏我錯了嗎？我的日期格式爲DD-MM-YY HH24:MI:SS。我正在使用Oracle數據庫。

SELECT dr1.pod_id, current_date() - dr1.daily_reading_date 
FROM (
    SELECT pod_id, 
      MIN(daily_reading_date) mindate 
    FROM daily_data_reading 
    GROUP BY pod_id 
    ) mini 
INNER JOIN daily_data_reading dr1 
    ON dr1.pod_id = mini.pod_id 
    AND dr1.daily_reading_date = mini.mindate 

Answer 1

Oracle支持CURRENT_DATE/SYSDATE不current_date()

SELECT dr1.pod_id, SYSDATE - dr1.daily_reading_date 
FROM (
    SELECT pod_id, 
      MIN(daily_reading_date) mindate 
    FROM daily_data_reading 
    GROUP BY pod_id 
    ) mini 
INNER JOIN daily_data_reading dr1 
    ON dr1.pod_id = mini.pod_id 
    AND dr1.daily_reading_date = mini.mindate 

（OR）

SELECT dr1.pod_id, CURRENT_DATE - dr1.daily_reading_date 
FROM (
    SELECT pod_id, 
      MIN(daily_reading_date) mindate 
    FROM daily_data_reading 
    GROUP BY pod_id 
    ) mini 
INNER JOIN daily_data_reading dr1 
    ON dr1.pod_id = mini.pod_id 
    AND dr1.daily_reading_date = mini.mindate 

Answer 2

，沒有自我聯接。 FIRST, LAST

select pod_id, 
CURRENT_DATE - MIN(daily_reading_date) KEEP (DENSE_RANK FIRST ORDER BY daily_reading_date) OVER (PARTITION BY pod_id) "LowestDateGroupedBYID" 
from 
daily_data_reading