如何選擇條件等於null的位置。

Question

SQL語句：

select * FROM Message
 WHERE senderId = 126 and receiverId = 125
   and dateReceived is null

HQL聲明：

 FROM Message
WHERE senderId = :senderId and receiverId = :receiverId
 and dateReceived is null

我出錯了。 那么如何編寫HQL以得到與上述sql語句相同的結果？

Answer 1

嘗試使用IS EMPTY應該可以。

Answer 2

是senderId和ReceiverId外鍵嗎？ 如果是，則假設senderId是Sender表的一列，並且receiveId是Receiver表的一列，請嘗試以下操作：

select msg FROM Message msg
 WHERE msg.Sender.senderId = 126 and msg.Receiver.receiverId = 125
   and msg.dateReceived is null

要么

Select msg FROM Message msg
WHERE msg.senderId = :senderId and msg.receiverId = :receiverId
 and msg.dateReceived is null

Answer 3

我已經解決了

HQL查詢：在消息來源中senderId =：senderId和receiverId =：receiverId和dateReceived = null