表格：
任務(wù)：id（bigint）名稱（varchar）。保存任務(wù)詳細(xì)資訊
作業(yè)：id(varchar(UUID)) task_id(bigint（類別ID）），staus >(varchar( 50)),created_time（時(shí)間戳記）。儲(chǔ)存任務(wù)執(zhí)行詳情
狀態(tài)的可能值為 FAIL/COMPLETED/INTERRUPTED
#我想要實(shí)現(xiàn)的是 從作業(yè)表中取得每個(gè)任務(wù)的所有最新值
如果任務(wù)中不存在作業(yè)，則傳回狀態(tài)為 null
SELECT
p.id, j.status
FROM
tas p
inner JOIN
job j ON j.task_id = p.id
inner JOIN
job j1 ON j.task_id = j1.task_id and j.create_time > j1.create_time; 
1
0
0
對(duì)於支援 ROW_NUMBER() 的 SQL 版本，您可以這樣做：
WITH info as(
SELECT
p.id,
j.status,
ROW_NUMBER() OVER(PARTITION BY p.id ORDER BY j.created_time DESC) AS rn
FROM tas p
LEFT JOIN job j ON j.task_id = p.id
)
SELECT id, status
FROM info
WHERE rn = 1
否則，只需使用 cte 或子查詢。
SELECT p.id, t.status FROM tas AS p LEFT JOIN ( SELECT task_id, MAX(created_time) as created_time FROM job GROUP BY task_id ) as lt ON p.id = lt.task_id LEFT JOIN task AS t ON lt.task_id = t.task_id AND lt.created_time = t.created_time
