在DELETE语句中指定“old than”

Question

我有一个查询，我想用它来删除“已查看”列日期时间值超过24小时的数据行。如何使用一个查询执行此操作？可能吗？

这是我到目前为止所做的：

$delete_expired_notifications_query= "DELETE FROM notifications WHERE user_id= 
'".$u_id."' AND viewed (some code that says older than 24hrs)";
    mysqli_query($connect, $delete_expired_notifications_query);

Answer 1

假设viewed是MySQL时态类型（它应该）：

... AND viewed < NOW() - INTERVAL 24 HOUR

Answer 2

使用date_Add和间隔，您可以尝试从现在开始超过24小时的记录..

DELETE FROM notifications WHERE user_id= 
'".$u_id."' AND viewed < date_Add(now(), interval - 24 hour)

Answer 3

DELETE FROM notifications WHERE user_id = '".$u_id."' 
      AND viewed < DATE_ADD(NOW(), INTERVAL -1 DAY)";

或

DELETE FROM notifications WHERE user_id = '".$u_id."' 
      AND viewed < DATE_ADD(NOW(), INTERVAL -24 HOUR)";