如何使用 PDO 从最后一个 ID 中选择前一个 ID

Question

我想从上一个id中选择上一个id。我该怎么做？ 数据库是 mysql.

示例：

id name
1   asd
2   adas
3   ads
4   dsf -> I want to choose this 
5   rew

id name  ---------------------------------------|
1   asd                                         |
2   adas                                        |
3   ads                                         |
4   dsf                                         |
5   rew -> I want to choose this if I add any "name"
6   zxc

到目前为止我试过这几行：

$sql = $db->prepare("SELECT * FROM answerController ORDER BY id DESC LIMIT 2");
$sql->execute();
$data = $sql->fetch();

Answer 1

您需要提供 offset 作为 limit 的开始。

SELECT * FROM answerController ORDER BY id DESC LIMIT 1, 2

https://dev.mysql.com/doc/refman/8.0/en/select.html

the first argument specifies the offset of the first row to return, and the second specifies the maximum number of rows to return. The offset of the initial row is 0 (not 1)

所以应该是：

$sql = $db->prepare("SELECT name FROM answerController ORDER BY id DESC LIMIT 1, 2");
$sql->execute();
$data = $sql->fetch(PDO::FETCH_ASSOC);
echo $data['name'];