Question

如何让以下查询按预期工作？ MySQL给出了多个ORDER BY

的错误

UPDATE user_list 
SET user_code = $code 
WHERE user_id = $id
AND country = $country AND 
     ((d = $d) OR 
     (c = $c ORDER BY c ASC LIMIT 1) OR
     (b = $b ORDER BY b ASC LIMIT 1))

这个想法如下：

如果有用户user_id = $id AND country = $country AND d = $d，则SET user_code = $code

如果上述情况属于假，那么请使用user_id = $id AND country = $country AND c = $c进行按c 订购的第一位用户，然后执行SET user_code = $code

如果上述情况属于假，那么请使用user_id = $id AND country = $country AND b = $b继续由b 订购的第一位用户，然后执行SET user_code = $code

Answer 1

您似乎想要更新c或b的最大值等于某个值的行。您可以使用连接执行此操作：

UPDATE user_list u CROSS JOIN
       (select max(c) as maxc, max(b) = maxb
        from user_list
        where user_id = $id AND country = $country
       ) uu
    SET user_code = $code
    WHERE user_id = $id AND country = $country AND
           ((d = $d) OR (c = maxc and c = $c) or (b = maxb and b = $b))

Answer 2

您可以使用嵌套的sql查找按c或b排序的第一个用户，我修改了您的原始命令。

UPDATE user_list 
SET user_code = $code 
WHERE user_id = $id
AND country = $country AND 
     ((d = $d) OR 
     ( $c = (select c from user_list order by c asc limit 1)) OR
     ( $b = (select b from user_list order by b asc limit 1)))

Mysql更新查询多个订单？

2 个答案: