有关同一列

Question

如何修复此查询？

SELECT COUNT(*)
FROM user_notifications
WHERE notification_status = '0'
  AND notification_sent_to = ?
  AND notification_category = 'ticket reply'
  AND notification_category = 'groupdoc'

我需要对结果过滤仅计算故障回复和groupdoc的通知类别。

非常感谢你的帮助。

Answer 1

列不能同时具有2个值。我想你想要的是OR

SELECT COUNT(*) 
FROM user_notifications 
WHERE notification_status = 0 AND notification_sent_to=? 
   AND (notification_category = 'ticket reply' OR notification_category= 'groupdoc')

Answer 2

特定列在给定行中只能有一个值。所以以下条件永远不会是真的

notification_category = 'ticket reply'AND notification_category= 'groupdoc'

当人们认为我需要值为'a'and行且值为'b'的行时，要使用的实际逻辑运算符为OR

SELECT COUNT(*) FROM user_notifications WHERE notification_status = '0' AND notification_sent_to=? AND
 (notification_category = 'ticket reply' OR notification_category= 'groupdoc')

Answer 3

使用in：

SELECT COUNT(*)
FROM user_notifications
WHERE notification_status = 0 AND
      notification_sent_to = ? AND
      notification_category IN ('ticket reply', 'groupdoc');