子查询在mysql中返回多于1行

Question

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。 欧麦尔

Answer 1

您可以通过限制子查询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“LIMIT 1”）

Answer 2

好吧，发生这种情况是因为您的子查询返回了不止一行

zerkms 来救援

ps：右侧“相关”栏中确实有很多类似的问题。

Answer 3

一种方法是将 LIMIT 1 添加到子查询中。另一种方法是确定子查询在逻辑上是否应该能够返回多于一行，如果不能，则修复它。