mysql - 连接表并按 2 个不同的列排序

Question

我有一个查询，列出了付款(付款表)，我希望它按任务的日期排序(2 个单独的表 - quotedb 和包装)这些付款与

我的查询:

SELECT a.* 
FROM payments AS a 
LEFT JOIN quotedb AS b ON a.orderid = b.id  
LEFT JOIN packaging AS p ON a.orderid = p.id  
WHERE a.status='Pending' AND (b.moveday<'$today' OR p.datestamp<'$today')
ORDER BY b.moveday, p.datestamp

付款表示例:

id payment   orderid
------------------- 
1  payment1  1
2  payment2  2
3  payment3  3
4  payment4  4
5  payment5  5
6  payment6  6

quotedb 表示例:

id moveday
-----------
1  05.07.18  > related to payments table id 1
2  08.07.18  
3  10.07.18

打包表示例:

id datestamp
-----------
4  06.07.18  > related to payments table id 4
5  07.07.18
6  19.07.18

我从表中加入结果，但排序有问题，查询似乎打印了未排序的“打包”表结果，然后是按移动日期排序的“quotedb”结果

我希望这些结果按(加入的 moveday 和 datestamp)排序

Answer 1

您可以使用UNION ALL 来合并quotedb 和packaging 表。并使用 grp 生成一个数字来生成 Order by 序号

SELECT a.* 
FROM payments a 
LEFT JOIN
(
    SELECT 1 grp,id,moveday AS day
    FROM quotedb
    UNION ALL
    SELECT 2,id,datestamp
    FROM packaging
) t on a.orderid = t.id
ORDER BY t.grp,t.day

sqlfiddle