如何获取MySQL中的最新值？

Question

如何获取每个artistID的最新值？我想获取 ww 和 ee (id=2,3)

    id  title   genreID  countryID  artistID  albumID  reg_count  down_count  createdAt           
------  ------  -------  ---------  --------  -------  ---------  ----------  ------------------- 
     1  qq            1          4         1        1         87          48  2020-05-05 01:00:00 
     2  ww            1          4         1        2         56          52  2020-05-05 03:00:00 
     3  ee            1          4         8       15         34          26  2020-05-05 21:00:00 
     4  rr            1          4         8       16         83          51  2020-05-05 05:00:00

Answer 1

在 MariaDB 10.2 或更高版本中，您可以使用 CTE 和 window 函数：

WITH CTE AS (
  SELECT *,
         ROW_NUMBER() OVER (PARTITION BY artistId ORDER BY createdAt DESC) AS rn
  FROM contentnew 
  WHERE genreID = 1 AND mainContent = 1 AND countryID = 4
)
SELECT id, title, genreID, countryID, artistID, albumID, reg_count, down_count, createdAt
FROM CTE
WHERE rn = 1

输出：

id  title   genreID     countryID   artistID    albumID     reg_count   down_count  createdAt
2   ww      1           4           1           2           56          52          2020-05-05 03:00:00
3   ee      1           4           8           15          34          26          2020-05-05 21:00:00

Demo on dbfiddle

如何获取MySQL中的最新值？

How to get the latest value in MySQL?

mysql

mariadb

groupwise-maximum