子查询在mysql中返回多于1行答案

【问题标题】：Subquery returns more than 1 row in mysql子查询在mysql中返回多于1行
【发布时间】：2011-03-22 06:52:28
【问题描述】：

我正在执行以下查询并收到错误“子查询返回超过 1 行”

我的查询是

SELECT pkTicketID,
       TicketReplyDateAdded,
       TIMESTAMPDIFF(DAY, TicketReplyDateAdded, now()) as NumberOfDays
  FROM tickets as T
    LEFT JOIN ticket_replies as TR ON T.fkTicketReplyID=TR.pkTicketReplyID
  WHERE 1 AND T.fkEmployeeID = '4'
    AND (SELECT TIMESTAMPDIFF(DAY, TicketReplyDateAdded, now()) as NumberOfDays
           FROM tickets as T
             LEFT JOIN ticket_replies as TR
               ON T.fkTicketReplyID=TR.pkTicketReplyID
        ) = 7
    AND T.TicketStatus = 'Replied'
  ORDER BY pkTicketReplyID DESC

感谢您的帮助。奥马尔

【问题讨论】：

标签： mysql sql mysql-error-1242

【解决方案1】：

您可以通过将子查询限制为仅返回一行来修复此错误，如下所示：

SELECT pkTicketID,TicketReplyDateAdded,
       TIMESTAMPDIFF(DAY, TicketReplyDateAdded,now()) as NumberOfDays 
FROM   tickets as T 
       LEFT JOIN ticket_replies as TR
       ON T.fkTicketReplyID=TR.pkTicketReplyID 
WHERE  1 
AND    T.fkEmployeeID = '4' 
AND    (SELECT TIMESTAMPDIFF(DAY, TicketReplyDateAdded, now()) as NumberOfDays 
        FROM tickets as T LEFT JOIN ticket_replies as TR 
        ON T.fkTicketReplyID=TR.pkTicketReplyID
        LIMIT 1) = 7 
AND     T.TicketStatus = 'Replied' 
ORDER   BY pkTicketReplyID DESC

（添加了“限制 1”）

【讨论】：

【解决方案2】：

嗯，这是因为您的子查询返回不止一行

zerkms 来救援

ps：右侧“相关”栏中确实有很多类似的问题。

【讨论】：

【解决方案3】：

一种方法是将LIMIT 1 添加到您的子查询中。另一个是确定您的子查询是否应该能够在逻辑上返回多行，如果不能，则修复它。

【讨论】：