mysql union order by 分別排序問題

標籤：

兩種方式：

第一種：

先各自排序，然後通過暫存資料表嵌套再合并結果，注意排序後面必須加入 limit，否則order by不起作用

SELECT * FROM (SELECT * FROM t1 WHERE id IN (1,3,6) ORDER BY utime DESC limit 5) AS a 
UNION ALL
SELECT * FROM (SELECT * FROM t1 WHERE id IN (2,4,5) ORDER BY utime DESC limit 5) AS b
;
第二種：

通過加入臨時列px查出所有結果後，再按px，utime排序

SELECT * FROM(
SELECT 0 AS px,id,NAME,utime FROM (SELECT * FROM t1 WHERE id IN (1,3,6)) AS a 
UNION ALL
SELECT  1 AS px,id,NAME,utime FROM (SELECT * FROM t1 WHERE id IN (2,4,5)  ) AS b
) AS c ORDER BY px,utime DESC

mysql union order by 分別排序問題